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提交 1f673135 编写于 作者: B bellard
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doc update 


git-svn-id: svn://svn.savannah.nongnu.org/qemu/trunk@705 c046a42c-6fe2-441c-8c8c-71466251a162
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Makefile
浏览文件 @ 1f673135
......@@ -11,7 +11,7 @@ ifndef CONFIG_WIN32
TOOLS=qemu-mkcow
endif
all: dyngen$(EXESUF) $(TOOLS) qemu-doc.html qemu.1
all: dyngen$(EXESUF) $(TOOLS) qemu-doc.html qemu-tech.html qemu.1
for d in $(TARGET_DIRS); do \
make -C $$d $@ || exit 1 ; \
done
......@@ -61,7 +61,7 @@ TAGS:
etags *.[ch] tests/*.[ch]
# documentation
qemu-doc.html: qemu-doc.texi
%.html: %.texi
texi2html -monolithic -number $<
qemu.1: qemu-doc.texi
......
TODO
浏览文件 @ 1f673135
......@@ -2,7 +2,6 @@ short term:
----------
- handle fast timers + add explicit clocks
- OS/2 install bug
- win 95 install bug
- handle Self Modifying Code even if modifying current TB (BE OS 5 install)
- physical memory cache (reduce qemu-fast address space size to about 32 MB)
- better code fetch
......
linux-2.6-qemu-fast.patch 0 → 100644
浏览文件 @ 1f673135
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .32324-linux-2.6.0/arch/i386/Kconfig .32324-linux-2.6.0.updated/arch/i386/Kconfig
--- .32324-linux-2.6.0/arch/i386/Kconfig 2003-10-09 18:02:48.000000000 +1000
+++ .32324-linux-2.6.0.updated/arch/i386/Kconfig 2003-12-26 16:46:49.000000000 +1100
@@ -307,6 +307,14 @@ config X86_GENERIC
when it has moderate overhead. This is intended for generic
distributions kernels.
+config QEMU
+ bool "Kernel to run under QEMU"
+ depends on EXPERIMENTAL
+ help
+ Select this if you want to boot the kernel inside qemu-fast,
+ the non-mmu version of the x86 emulator. See
+ <http://fabrice.bellard.free.fr/qemu/>. Say N.
+
#
# Define implied options from the CPU selection here
#
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .32324-linux-2.6.0/arch/i386/kernel/Makefile .32324-linux-2.6.0.updated/arch/i386/kernel/Makefile
--- .32324-linux-2.6.0/arch/i386/kernel/Makefile 2003-09-29 10:25:15.000000000 +1000
+++ .32324-linux-2.6.0.updated/arch/i386/kernel/Makefile 2003-12-26 16:46:49.000000000 +1100
@@ -46,12 +46,14 @@ quiet_cmd_syscall = SYSCALL $@
cmd_syscall = $(CC) -nostdlib $(SYSCFLAGS_$(@F)) \
-Wl,-T,$(filter-out FORCE,$^) -o $@
+export AFLAGS_vsyscall.lds.o += -P -C -U$(ARCH)
+
vsyscall-flags = -shared -s -Wl,-soname=linux-gate.so.1
SYSCFLAGS_vsyscall-sysenter.so = $(vsyscall-flags)
SYSCFLAGS_vsyscall-int80.so = $(vsyscall-flags)
$(obj)/vsyscall-int80.so $(obj)/vsyscall-sysenter.so: \
-$(obj)/vsyscall-%.so: $(src)/vsyscall.lds $(obj)/vsyscall-%.o FORCE
+$(obj)/vsyscall-%.so: $(src)/vsyscall.lds.s $(obj)/vsyscall-%.o FORCE
$(call if_changed,syscall)
# We also create a special relocatable object that should mirror the symbol
@@ -62,5 +64,5 @@ $(obj)/built-in.o: $(obj)/vsyscall-syms.
$(obj)/built-in.o: ld_flags += -R $(obj)/vsyscall-syms.o
SYSCFLAGS_vsyscall-syms.o = -r
-$(obj)/vsyscall-syms.o: $(src)/vsyscall.lds $(obj)/vsyscall-sysenter.o FORCE
+$(obj)/vsyscall-syms.o: $(src)/vsyscall.lds.s $(obj)/vsyscall-sysenter.o FORCE
$(call if_changed,syscall)
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .32324-linux-2.6.0/arch/i386/kernel/vmlinux.lds.S .32324-linux-2.6.0.updated/arch/i386/kernel/vmlinux.lds.S
--- .32324-linux-2.6.0/arch/i386/kernel/vmlinux.lds.S 2003-09-22 10:27:28.000000000 +1000
+++ .32324-linux-2.6.0.updated/arch/i386/kernel/vmlinux.lds.S 2003-12-26 16:46:49.000000000 +1100
@@ -3,6 +3,7 @@
*/
#include <asm-generic/vmlinux.lds.h>
+#include <asm/page.h>
OUTPUT_FORMAT("elf32-i386", "elf32-i386", "elf32-i386")
OUTPUT_ARCH(i386)
@@ -10,7 +11,7 @@ ENTRY(startup_32)
jiffies = jiffies_64;
SECTIONS
{
- . = 0xC0000000 + 0x100000;
+ . = __PAGE_OFFSET + 0x100000;
/* read-only */
_text = .; /* Text and read-only data */
.text : {
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .32324-linux-2.6.0/arch/i386/kernel/vsyscall.lds .32324-linux-2.6.0.updated/arch/i386/kernel/vsyscall.lds
--- .32324-linux-2.6.0/arch/i386/kernel/vsyscall.lds 2003-09-22 10:07:26.000000000 +1000
+++ .32324-linux-2.6.0.updated/arch/i386/kernel/vsyscall.lds 1970-01-01 10:00:00.000000000 +1000
@@ -1,67 +0,0 @@
-/*
- * Linker script for vsyscall DSO. The vsyscall page is an ELF shared
- * object prelinked to its virtual address, and with only one read-only
- * segment (that fits in one page). This script controls its layout.
- */
-
-/* This must match <asm/fixmap.h>. */
-VSYSCALL_BASE = 0xffffe000;
-
-SECTIONS
-{
- . = VSYSCALL_BASE + SIZEOF_HEADERS;
-
- .hash : { *(.hash) } :text
- .dynsym : { *(.dynsym) }
- .dynstr : { *(.dynstr) }
- .gnu.version : { *(.gnu.version) }
- .gnu.version_d : { *(.gnu.version_d) }
- .gnu.version_r : { *(.gnu.version_r) }
-
- /* This linker script is used both with -r and with -shared.
- For the layouts to match, we need to skip more than enough
- space for the dynamic symbol table et al. If this amount
- is insufficient, ld -shared will barf. Just increase it here. */
- . = VSYSCALL_BASE + 0x400;
-
- .text : { *(.text) } :text =0x90909090
-
- .eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr
- .eh_frame : { KEEP (*(.eh_frame)) } :text
- .dynamic : { *(.dynamic) } :text :dynamic
- .useless : {
- *(.got.plt) *(.got)
- *(.data .data.* .gnu.linkonce.d.*)
- *(.dynbss)
- *(.bss .bss.* .gnu.linkonce.b.*)
- } :text
-}
-
-/*
- * We must supply the ELF program headers explicitly to get just one
- * PT_LOAD segment, and set the flags explicitly to make segments read-only.
- */
-PHDRS
-{
- text PT_LOAD FILEHDR PHDRS FLAGS(5); /* PF_R|PF_X */
- dynamic PT_DYNAMIC FLAGS(4); /* PF_R */
- eh_frame_hdr 0x6474e550; /* PT_GNU_EH_FRAME, but ld doesn't match the name */
-}
-
-/*
- * This controls what symbols we export from the DSO.
- */
-VERSION
-{
- LINUX_2.5 {
- global:
- __kernel_vsyscall;
- __kernel_sigreturn;
- __kernel_rt_sigreturn;
-
- local: *;
- };
-}
-
-/* The ELF entry point can be used to set the AT_SYSINFO value. */
-ENTRY(__kernel_vsyscall);
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .32324-linux-2.6.0/arch/i386/kernel/vsyscall.lds.S .32324-linux-2.6.0.updated/arch/i386/kernel/vsyscall.lds.S
--- .32324-linux-2.6.0/arch/i386/kernel/vsyscall.lds.S 1970-01-01 10:00:00.000000000 +1000
+++ .32324-linux-2.6.0.updated/arch/i386/kernel/vsyscall.lds.S 2003-12-26 16:46:49.000000000 +1100
@@ -0,0 +1,67 @@
+/*
+ * Linker script for vsyscall DSO. The vsyscall page is an ELF shared
+ * object prelinked to its virtual address, and with only one read-only
+ * segment (that fits in one page). This script controls its layout.
+ */
+#include <asm/fixmap.h>
+
+VSYSCALL_BASE = __FIXADDR_TOP - 0x1000;
+
+SECTIONS
+{
+ . = VSYSCALL_BASE + SIZEOF_HEADERS;
+
+ .hash : { *(.hash) } :text
+ .dynsym : { *(.dynsym) }
+ .dynstr : { *(.dynstr) }
+ .gnu.version : { *(.gnu.version) }
+ .gnu.version_d : { *(.gnu.version_d) }
+ .gnu.version_r : { *(.gnu.version_r) }
+
+ /* This linker script is used both with -r and with -shared.
+ For the layouts to match, we need to skip more than enough
+ space for the dynamic symbol table et al. If this amount
+ is insufficient, ld -shared will barf. Just increase it here. */
+ . = VSYSCALL_BASE + 0x400;
+
+ .text : { *(.text) } :text =0x90909090
+
+ .eh_frame_hdr : { *(.eh_frame_hdr) } :text :eh_frame_hdr
+ .eh_frame : { KEEP (*(.eh_frame)) } :text
+ .dynamic : { *(.dynamic) } :text :dynamic
+ .useless : {
+ *(.got.plt) *(.got)
+ *(.data .data.* .gnu.linkonce.d.*)
+ *(.dynbss)
+ *(.bss .bss.* .gnu.linkonce.b.*)
+ } :text
+}
+
+/*
+ * We must supply the ELF program headers explicitly to get just one
+ * PT_LOAD segment, and set the flags explicitly to make segments read-only.
+ */
+PHDRS
+{
+ text PT_LOAD FILEHDR PHDRS FLAGS(5); /* PF_R|PF_X */
+ dynamic PT_DYNAMIC FLAGS(4); /* PF_R */
+ eh_frame_hdr 0x6474e550; /* PT_GNU_EH_FRAME, but ld doesn't match the name */
+}
+
+/*
+ * This controls what symbols we export from the DSO.
+ */
+VERSION
+{
+ LINUX_2.5 {
+ global:
+ __kernel_vsyscall;
+ __kernel_sigreturn;
+ __kernel_rt_sigreturn;
+
+ local: *;
+ };
+}
+
+/* The ELF entry point can be used to set the AT_SYSINFO value. */
+ENTRY(__kernel_vsyscall);
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .32324-linux-2.6.0/include/asm-i386/fixmap.h .32324-linux-2.6.0.updated/include/asm-i386/fixmap.h
--- .32324-linux-2.6.0/include/asm-i386/fixmap.h 2003-09-22 10:09:12.000000000 +1000
+++ .32324-linux-2.6.0.updated/include/asm-i386/fixmap.h 2003-12-26 16:46:49.000000000 +1100
@@ -14,6 +14,19 @@
#define _ASM_FIXMAP_H
#include <linux/config.h>
+
+/* used by vmalloc.c, vsyscall.lds.S.
+ *
+ * Leave one empty page between vmalloc'ed areas and
+ * the start of the fixmap.
+ */
+#ifdef CONFIG_QEMU
+#define __FIXADDR_TOP 0xa7fff000
+#else
+#define __FIXADDR_TOP 0xfffff000
+#endif
+
+#ifndef __ASSEMBLY__
#include <linux/kernel.h>
#include <asm/acpi.h>
#include <asm/apicdef.h>
@@ -94,13 +107,8 @@ extern void __set_fixmap (enum fixed_add
#define clear_fixmap(idx) \
__set_fixmap(idx, 0, __pgprot(0))
-/*
- * used by vmalloc.c.
- *
- * Leave one empty page between vmalloc'ed areas and
- * the start of the fixmap.
- */
-#define FIXADDR_TOP (0xfffff000UL)
+#define FIXADDR_TOP ((unsigned long)__FIXADDR_TOP)
+
#define __FIXADDR_SIZE (__end_of_permanent_fixed_addresses << PAGE_SHIFT)
#define FIXADDR_START (FIXADDR_TOP - __FIXADDR_SIZE)
@@ -145,4 +153,5 @@ static inline unsigned long virt_to_fix(
return __virt_to_fix(vaddr);
}
+#endif /* !__ASSEMBLY__ */
#endif
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .32324-linux-2.6.0/include/asm-i386/page.h .32324-linux-2.6.0.updated/include/asm-i386/page.h
--- .32324-linux-2.6.0/include/asm-i386/page.h 2003-09-22 10:06:42.000000000 +1000
+++ .32324-linux-2.6.0.updated/include/asm-i386/page.h 2003-12-26 16:46:49.000000000 +1100
@@ -10,10 +10,10 @@
#define LARGE_PAGE_SIZE (1UL << PMD_SHIFT)
#ifdef __KERNEL__
-#ifndef __ASSEMBLY__
-
#include <linux/config.h>
+#ifndef __ASSEMBLY__
+
#ifdef CONFIG_X86_USE_3DNOW
#include <asm/mmx.h>
@@ -115,12 +115,19 @@ static __inline__ int get_order(unsigned
#endif /* __ASSEMBLY__ */
#ifdef __ASSEMBLY__
+#ifdef CONFIG_QEMU
+#define __PAGE_OFFSET (0x90000000)
+#else
#define __PAGE_OFFSET (0xC0000000)
+#endif /* QEMU */
+#else
+#ifdef CONFIG_QEMU
+#define __PAGE_OFFSET (0x90000000UL)
#else
#define __PAGE_OFFSET (0xC0000000UL)
+#endif /* QEMU */
#endif
-
#define PAGE_OFFSET ((unsigned long)__PAGE_OFFSET)
#define VMALLOC_RESERVE ((unsigned long)__VMALLOC_RESERVE)
#define MAXMEM (-__PAGE_OFFSET-__VMALLOC_RESERVE)
diff -urpN --exclude TAGS -X /home/rusty/devel/kernel/kernel-patches/current-dontdiff --minimal .32324-linux-2.6.0/include/asm-i386/param.h .32324-linux-2.6.0.updated/include/asm-i386/param.h
--- .32324-linux-2.6.0/include/asm-i386/param.h 2003-09-21 17:26:06.000000000 +1000
+++ .32324-linux-2.6.0.updated/include/asm-i386/param.h 2003-12-26 16:46:49.000000000 +1100
@@ -2,7 +2,12 @@
#define _ASMi386_PARAM_H
#ifdef __KERNEL__
-# define HZ 1000 /* Internal kernel timer frequency */
+# include <linux/config.h>
+# ifdef CONFIG_QEMU
+# define HZ 100
+# else
+# define HZ 1000 /* Internal kernel timer frequency */
+# endif
# define USER_HZ 100 /* .. some user interfaces are in "ticks" */
# define CLOCKS_PER_SEC (USER_HZ) /* like times() */
#endif
qemu-doc.texi
浏览文件 @ 1f673135
\input texinfo @c -*- texinfo -*-
@iftex
@settitle QEMU CPU Emulator Reference Documentation
@settitle QEMU CPU Emulator User Documentation
@titlepage
@sp 7
@center @titlefont{QEMU CPU Emulator Reference Documentation}
@center @titlefont{QEMU CPU Emulator User Documentation}
@sp 3
@end titlepage
@end iftex
......@@ -13,126 +13,39 @@
@section Features
QEMU is a FAST! processor emulator. By using dynamic translation it
achieves a reasonnable speed while being easy to port on new host
CPUs.
QEMU is a FAST! processor emulator using dynamic translation to
achieve good emulation speed.
QEMU has two operating modes:
@itemize @minus
@item
User mode emulation. In this mode, QEMU can launch Linux processes
compiled for one CPU on another CPU. Linux system calls are converted
because of endianness and 32/64 bit mismatches. The Wine Windows API
emulator (@url{http://www.winehq.org}) and the DOSEMU DOS emulator
(@url{http://www.dosemu.org}) are the main targets for QEMU.
Full system emulation. In this mode, QEMU emulates a full system (for
example a PC), including a processor and various peripherials. It can
be used to launch different Operating Systems without rebooting the
PC or to debug system code.
@item
Full system emulation. In this mode, QEMU emulates a full
system, including a processor and various peripherials. Currently, it
is only used to launch an x86 Linux kernel on an x86 Linux system. It
enables easier testing and debugging of system code. It can also be
used to provide virtual hosting of several virtual PCs on a single
server.
User mode emulation (Linux host only). In this mode, QEMU can launch
Linux processes compiled for one CPU on another CPU. It can be used to
launch the Wine Windows API emulator (@url{http://www.winehq.org}) or
to ease cross-compilation and cross-debugging.
@end itemize
As QEMU requires no host kernel patches to run, it is very safe and
As QEMU requires no host kernel driver to run, it is very safe and
easy to use.
QEMU generic features:
For system emulation, only the x86 PC emulator is currently
usable. The PowerPC system emulator is being developped.
@itemize
@item User space only or full system emulation.
@item Using dynamic translation to native code for reasonnable speed.
@item Working on x86 and PowerPC hosts. Being tested on ARM, Sparc32, Alpha and S390.
@item Self-modifying code support.
@item Precise exceptions support.
@item The virtual CPU is a library (@code{libqemu}) which can be used
in other projects.
@end itemize
QEMU user mode emulation features:
@itemize
@item Generic Linux system call converter, including most ioctls.
@item clone() emulation using native CPU clone() to use Linux scheduler for threads.
@item Accurate signal handling by remapping host signals to target signals.
@end itemize
@end itemize
QEMU full system emulation features:
@itemize
@item QEMU can either use a full software MMU for maximum portability or use the host system call mmap() to simulate the target MMU.
@end itemize
@section x86 emulation
QEMU x86 target features:
@itemize
@item The virtual x86 CPU supports 16 bit and 32 bit addressing with segmentation.
LDT/GDT and IDT are emulated. VM86 mode is also supported to run DOSEMU.
@item Support of host page sizes bigger than 4KB in user mode emulation.
@item QEMU can emulate itself on x86.
@item An extensive Linux x86 CPU test program is included @file{tests/test-i386}.
It can be used to test other x86 virtual CPUs.
@end itemize
Current QEMU limitations:
@itemize
@item No SSE/MMX support (yet).
@item No x86-64 support.
@item IPC syscalls are missing.
@item The x86 segment limits and access rights are not tested at every
memory access.
@item On non x86 host CPUs, @code{double}s are used instead of the non standard
10 byte @code{long double}s of x86 for floating point emulation to get
maximum performances.
@item Some priviledged instructions or behaviors are missing, especially for segment protection testing (yet).
@end itemize
@section ARM emulation
@itemize
@item ARM emulation can currently launch small programs while using the
generic dynamic code generation architecture of QEMU.
@item No FPU support (yet).
@item No automatic regression testing (yet).
@end itemize
@section SPARC emulation
The SPARC emulation is currently in development.
For user emulation, x86, PowerPC, ARM, and SPARC CPUs are supported.
@chapter Installation
@section Linux
If you want to compile QEMU, please read the @file{README} which gives
the related information. Otherwise just download the binary
distribution (@file{qemu-XXX-i386.tar.gz}) and untar it as root in
......@@ -144,106 +57,69 @@ cd /
tar zxvf /tmp/qemu-XXX-i386.tar.gz
@end example
@chapter QEMU User space emulator invocation
@section Quick Start
In order to launch a Linux process, QEMU needs the process executable
itself and all the target (x86) dynamic libraries used by it.
@section Windows
w
@itemize
@item Install the current versions of MSYS and MinGW from
@url{http://www.mingw.org/}. You can find detailed installation
instructions in the download section and the FAQ.
@item On x86, you can just try to launch any process by using the native
libraries:
@example
qemu-i386 -L / /bin/ls
@end example
@item Download
the MinGW development library of SDL 1.2.x
(@file{SDL-devel-1.2.x-mingw32.tar.gz}) from
@url{http://www.libsdl.org}. Unpack it in a temporary place, and
unpack the archive @file{i386-mingw32msvc.tar.gz} in the MinGW tool
directory. Edit the @file{sdl-config} script so that it gives the
correct SDL directory when invoked.
@code{-L /} tells that the x86 dynamic linker must be searched with a
@file{/} prefix.
@item Extract the current version of QEMU.
@item Since QEMU is also a linux process, you can launch qemu with qemu (NOTE: you can only do that if you compiled QEMU from the sources):
@item Start the MSYS shell (file @file{msys.bat}).
@example
qemu-i386 -L / qemu-i386 -L / /bin/ls
@end example
@item Change to the QEMU directory. Launch @file{./configure} and
@file{make}. If you have problems using SDL, verify that
@file{sdl-config} can be launched from the MSYS command line.
@item On non x86 CPUs, you need first to download at least an x86 glibc
(@file{qemu-runtime-i386-XXX-.tar.gz} on the QEMU web page). Ensure that
@code{LD_LIBRARY_PATH} is not set:
@example
unset LD_LIBRARY_PATH
@end example
Then you can launch the precompiled @file{ls} x86 executable:
@example
qemu-i386 tests/i386/ls
@end example
You can look at @file{qemu-binfmt-conf.sh} so that
QEMU is automatically launched by the Linux kernel when you try to
launch x86 executables. It requires the @code{binfmt_misc} module in the
Linux kernel.
@item The x86 version of QEMU is also included. You can try weird things such as:
@example
qemu-i386 /usr/local/qemu-i386/bin/qemu-i386 /usr/local/qemu-i386/bin/ls-i386
@end example
@item You can install QEMU in @file{Program Files/Qemu} by typing
@file{make install}. Don't forget to copy @file{SDL.dll} in
@file{Program Files/Qemu}.
@end itemize
@section Wine launch
@section Cross compilation for Windows with Linux
@itemize
@item
Install the MinGW cross compilation tools available at
@url{http://www.mingw.org/}.
@item Ensure that you have a working QEMU with the x86 glibc
distribution (see previous section). In order to verify it, you must be
able to do:
@item
Install the Win32 version of SDL (@url{http://www.libsdl.org}) by
unpacking @file{i386-mingw32msvc.tar.gz}. Set up the PATH environment
variable so that @file{i386-mingw32msvc-sdl-config} can be launched by
the QEMU configuration script.
@item
Configure QEMU for Windows cross compilation:
@example
qemu-i386 /usr/local/qemu-i386/bin/ls-i386
./configure --enable-mingw32
@end example
If necessary, you can change the cross-prefix according to the prefix
choosen for the MinGW tools with --cross-prefix. You can also use
--prefix to set the Win32 install path.
@item Download the binary x86 Wine install
(@file{qemu-XXX-i386-wine.tar.gz} on the QEMU web page).
@item Configure Wine on your account. Look at the provided script
@file{/usr/local/qemu-i386/bin/wine-conf.sh}. Your previous
@code{$@{HOME@}/.wine} directory is saved to @code{$@{HOME@}/.wine.org}.
@item Then you can try the example @file{putty.exe}:
@example
qemu-i386 /usr/local/qemu-i386/wine/bin/wine /usr/local/qemu-i386/wine/c/Program\ Files/putty.exe
@end example
@item You can install QEMU in the installation directory by typing
@file{make install}. Don't forget to copy @file{SDL.dll} in the
installation directory.
@end itemize
@section Command line options
Note: Currently, Wine does not seem able to launch
QEMU for Win32.
@example
usage: qemu-i386 [-h] [-d] [-L path] [-s size] program [arguments...]
@end example
@section Mac OS X
@table @option
@item -h
Print the help
@item -L path
Set the x86 elf interpreter prefix (default=/usr/local/qemu-i386)
@item -s size
Set the x86 stack size in bytes (default=524288)
@end table
Debug options:
@table @option
@item -d
Activate log (logfile=/tmp/qemu.log)
@item -p pagesize
Act as if the host page size was 'pagesize' bytes
@end table
Mac OS X is currently not supported.
@chapter QEMU System emulator invocation
......@@ -251,9 +127,7 @@ Act as if the host page size was 'pagesize' bytes
@c man begin DESCRIPTION
The QEMU System emulator simulates a complete PC. It can either boot
directly a Linux kernel (without any BIOS or boot loader) or boot like a
real PC with the included BIOS.
The QEMU System emulator simulates a complete PC.
In order to meet specific user needs, two versions of QEMU are
available:
......@@ -283,17 +157,13 @@ PS/2 mouse and keyboard
@item
2 IDE interfaces with hard disk and CD-ROM support
@item
NE2000 network adapter (port=0x300, irq=9)
Floppy disk
@item
up to 6 NE2000 network adapters
@item
Serial port
@item
Soundblaster 16 card
@item
PIC (interrupt controler)
@item
PIT (timers)
@item
CMOS memory
@end itemize
@c man end
......@@ -308,157 +178,6 @@ qemu linux.img
Linux should boot and give you a prompt.
@section Direct Linux Boot and Network emulation
This section explains how to launch a Linux kernel inside QEMU without
having to make a full bootable image. It is very useful for fast Linux
kernel testing. The QEMU network configuration is also explained.
@enumerate
@item
Download the archive @file{linux-test-xxx.tar.gz} containing a Linux
kernel and a disk image.
@item Optional: If you want network support (for example to launch X11 examples), you
must copy the script @file{qemu-ifup} in @file{/etc} and configure
properly @code{sudo} so that the command @code{ifconfig} contained in
@file{qemu-ifup} can be executed as root. You must verify that your host
kernel supports the TUN/TAP network interfaces: the device
@file{/dev/net/tun} must be present.
When network is enabled, there is a virtual network connection between
the host kernel and the emulated kernel. The emulated kernel is seen
from the host kernel at IP address 172.20.0.2 and the host kernel is
seen from the emulated kernel at IP address 172.20.0.1.
@item Launch @code{qemu.sh}. You should have the following output:
@example
> ./qemu.sh
Connected to host network interface: tun0
Linux version 2.4.21 (bellard@voyager.localdomain) (gcc version 3.2.2 20030222 (Red Hat Linux 3.2.2-5)) #5 Tue Nov 11 18:18:53 CET 2003
BIOS-provided physical RAM map:
BIOS-e801: 0000000000000000 - 000000000009f000 (usable)
BIOS-e801: 0000000000100000 - 0000000002000000 (usable)
32MB LOWMEM available.
On node 0 totalpages: 8192
zone(0): 4096 pages.
zone(1): 4096 pages.
zone(2): 0 pages.
Kernel command line: root=/dev/hda sb=0x220,5,1,5 ide2=noprobe ide3=noprobe ide4=noprobe ide5=noprobe console=ttyS0
ide_setup: ide2=noprobe
ide_setup: ide3=noprobe
ide_setup: ide4=noprobe
ide_setup: ide5=noprobe
Initializing CPU#0
Detected 2399.621 MHz processor.
Console: colour EGA 80x25
Calibrating delay loop... 4744.80 BogoMIPS
Memory: 28872k/32768k available (1210k kernel code, 3508k reserved, 266k data, 64k init, 0k highmem)
Dentry cache hash table entries: 4096 (order: 3, 32768 bytes)
Inode cache hash table entries: 2048 (order: 2, 16384 bytes)
Mount cache hash table entries: 512 (order: 0, 4096 bytes)
Buffer-cache hash table entries: 1024 (order: 0, 4096 bytes)
Page-cache hash table entries: 8192 (order: 3, 32768 bytes)
CPU: Intel Pentium Pro stepping 03
Checking 'hlt' instruction... OK.
POSIX conformance testing by UNIFIX
Linux NET4.0 for Linux 2.4
Based upon Swansea University Computer Society NET3.039
Initializing RT netlink socket
apm: BIOS not found.
Starting kswapd
Journalled Block Device driver loaded
Detected PS/2 Mouse Port.
pty: 256 Unix98 ptys configured
Serial driver version 5.05c (2001-07-08) with no serial options enabled
ttyS00 at 0x03f8 (irq = 4) is a 16450
ne.c:v1.10 9/23/94 Donald Becker (becker@scyld.com)
Last modified Nov 1, 2000 by Paul Gortmaker
NE*000 ethercard probe at 0x300: 52 54 00 12 34 56
eth0: NE2000 found at 0x300, using IRQ 9.
RAMDISK driver initialized: 16 RAM disks of 4096K size 1024 blocksize
Uniform Multi-Platform E-IDE driver Revision: 7.00beta4-2.4
ide: Assuming 50MHz system bus speed for PIO modes; override with idebus=xx
hda: QEMU HARDDISK, ATA DISK drive
ide0 at 0x1f0-0x1f7,0x3f6 on irq 14
hda: attached ide-disk driver.
hda: 20480 sectors (10 MB) w/256KiB Cache, CHS=20/16/63
Partition check:
hda:
Soundblaster audio driver Copyright (C) by Hannu Savolainen 1993-1996
NET4: Linux TCP/IP 1.0 for NET4.0
IP Protocols: ICMP, UDP, TCP, IGMP
IP: routing cache hash table of 512 buckets, 4Kbytes
TCP: Hash tables configured (established 2048 bind 4096)
NET4: Unix domain sockets 1.0/SMP for Linux NET4.0.
EXT2-fs warning: mounting unchecked fs, running e2fsck is recommended
VFS: Mounted root (ext2 filesystem).
Freeing unused kernel memory: 64k freed
Linux version 2.4.21 (bellard@voyager.localdomain) (gcc version 3.2.2 20030222 (Red Hat Linux 3.2.2-5)) #5 Tue Nov 11 18:18:53 CET 2003
QEMU Linux test distribution (based on Redhat 9)
Type 'exit' to halt the system
sh-2.05b#
@end example
@item
Then you can play with the kernel inside the virtual serial console. You
can launch @code{ls} for example. Type @key{Ctrl-a h} to have an help
about the keys you can type inside the virtual serial console. In
particular, use @key{Ctrl-a x} to exit QEMU and use @key{Ctrl-a b} as
the Magic SysRq key.
@item
If the network is enabled, launch the script @file{/etc/linuxrc} in the
emulator (don't forget the leading dot):
@example
. /etc/linuxrc
@end example
Then enable X11 connections on your PC from the emulated Linux:
@example
xhost +172.20.0.2
@end example
You can now launch @file{xterm} or @file{xlogo} and verify that you have
a real Virtual Linux system !
@end enumerate
NOTES:
@enumerate
@item
A 2.5.74 kernel is also included in the archive. Just
replace the bzImage in qemu.sh to try it.
@item
qemu creates a temporary file in @var{$QEMU_TMPDIR} (@file{/tmp} is the
default) containing all the simulated PC memory. If possible, try to use
a temporary directory using the tmpfs filesystem to avoid too many
unnecessary disk accesses.
@item
In order to exit cleanly from qemu, you can do a @emph{shutdown} inside
qemu. qemu will automatically exit when the Linux shutdown is done.
@item
You can boot slightly faster by disabling the probe of non present IDE
interfaces. To do so, add the following options on the kernel command
line:
@example
ide1=noprobe ide2=noprobe ide3=noprobe ide4=noprobe ide5=noprobe
@end example
@item
The example disk image is a modified version of the one made by Kevin
Lawton for the plex86 Project (@url{www.plex86.org}).
@end enumerate
@section Invocation
@example
......@@ -486,8 +205,8 @@ Use @var{file} as hard disk 0, 1, 2 or 3 image (@xref{disk_images}).
Use @var{file} as CD-ROM image (you cannot use @option{-hdc} and and
@option{-cdrom} at the same time).
@item -boot [a|b|c|d]
Boot on floppy (a, b), hard disk (c) or CD-ROM (d). Hard disk boot is
@item -boot [a|c|d]
Boot on floppy (a), hard disk (c) or CD-ROM (d). Hard disk boot is
the default.
@item -snapshot
......@@ -498,19 +217,9 @@ the write back by pressing @key{C-a s} (@xref{disk_images}).
@item -m megs
Set virtual RAM size to @var{megs} megabytes.
@item -n script
Set network init script [default=/etc/qemu-ifup]. This script is
launched to configure the host network interface (usually tun0)
corresponding to the virtual NE2000 card.
@item -initrd file
Use @var{file} as initial ram disk.
@item -tun-fd fd
Assumes @var{fd} talks to tap/tun and use it. Read
@url{http://bellard.org/qemu/tetrinet.html} to have an example of its
use.
@item -nographic
Normally, QEMU uses SDL to display the VGA output. With this option,
......@@ -521,7 +230,35 @@ with a serial console.
@end table
Linux boot specific (does not require a full PC boot with a BIOS):
Network options:
@table @option
@item -n script
Set network init script [default=/etc/qemu-ifup]. This script is
launched to configure the host network interface (usually tun0)
corresponding to the virtual NE2000 card.
@item nics n
Simulate @var{n} network interfaces (default=1).
@item -macaddr addr
Set the mac address of the first interface (the format is
aa:bb:cc:dd:ee:ff in hexa). The mac address is incremented for each
new network interface.
@item -tun-fd fd1,...
Assumes @var{fd} talks to tap/tun and use it. Read
@url{http://bellard.org/qemu/tetrinet.html} to have an example of its
use.
@end table
Linux boot specific. When using this options, you can use a given
Linux kernel without installing it in the disk image. It can be useful
for easier testing of various kernels.
@table @option
@item -kernel bzImage
......@@ -545,7 +282,8 @@ Change gdb connection port.
Output log in /tmp/qemu.log
@end table
During emulation, use @key{C-a h} to get terminal commands:
During emulation, if you are using the serial console, use @key{C-a h}
to get terminal commands:
@table @key
@item C-a h
......@@ -555,7 +293,9 @@ Exit emulatior
@item C-a s
Save disk data back to file (if -snapshot)
@item C-a b
Send break (magic sysrq)
Send break (magic sysrq in Linux)
@item C-a c
Switch between console and monitor
@item C-a C-a
Send C-a
@end table
......@@ -566,18 +306,165 @@ Send C-a
@setfilename qemu
@settitle QEMU System Emulator
@c man begin SEEALSO
The HTML documentation of QEMU for more precise information and Linux
user mode emulator invocation.
@c man end
@c man begin SEEALSO
The HTML documentation of QEMU for more precise information and Linux
user mode emulator invocation.
@c man end
@c man begin AUTHOR
Fabrice Bellard
@c man end
@end ignore
@end ignore
@section QEMU Monitor
The QEMU monitor is used to give complex commands to the QEMU
emulator. You can use it to:
@itemize @minus
@item
Remove or insert removable medias images
(such as CD-ROM or floppies)
@item
Freeze/unfreeze the Virtual Machine (VM) and save or restore its state
from a disk file.
@item Inspect the VM state without an external debugger.
@end itemize
@subsection Commands
The following commands are available:
@table @option
@item help or ? [cmd]
Show the help for all commands or just for command @var{cmd}.
@item commit
Commit changes to the disk images (if -snapshot is used)
@item info subcommand
show various information about the system state
@table @option
@item info network
show the network state
@item info block
show the block devices
@item info registers
show the cpu registers
@item info history
show the command line history
@end table
@item q or quit
Quit the emulator.
@item eject [-f] device
Eject a removable media (use -f to force it).
@item change device filename
Change a removable media.
@item screendump filename
Save screen into PPM image @var{filename}.
@item log item1[,...]
Activate logging of the specified items to @file{/tmp/qemu.log}.
@item savevm filename
Save the whole virtual machine state to @var{filename}.
@item loadvm filename
Restore the whole virtual machine state from @var{filename}.
@item stop
Stop emulation.
@item c or cont
Resume emulation.
@item gdbserver [port]
Start gdbserver session (default port=1234)
@item x/fmt addr
Virtual memory dump starting at @var{addr}.
@item xp /fmt addr
Physical memory dump starting at @var{addr}.
@var{fmt} is a format which tells the command how to format the
data. Its syntax is: @option{/@{count@}@{format@}@{size@}}
@table @var
@item count
is the number of items to be dumped.
@item format
can be x (hexa), d (signed decimal), u (unsigned decimal), o (octal),
c (char) or i (asm instruction).
@item size
can be b (8 bits), h (16 bits), w (32 bits) or g (64 bits)
@end table
Examples:
@itemize
@item
Dump 10 instructions at the current instruction pointer:
@example
(qemu) x/10i $eip
0x90107063: ret
0x90107064: sti
0x90107065: lea 0x0(%esi,1),%esi
0x90107069: lea 0x0(%edi,1),%edi
0x90107070: ret
0x90107071: jmp 0x90107080
0x90107073: nop
0x90107074: nop
0x90107075: nop
0x90107076: nop
@end example
@item
Dump 80 16 bit values at the start of the video memory.
@example
(qemu) xp/80hx 0xb8000
0x000b8000: 0x0b50 0x0b6c 0x0b65 0x0b78 0x0b38 0x0b36 0x0b2f 0x0b42
0x000b8010: 0x0b6f 0x0b63 0x0b68 0x0b73 0x0b20 0x0b56 0x0b47 0x0b41
0x000b8020: 0x0b42 0x0b69 0x0b6f 0x0b73 0x0b20 0x0b63 0x0b75 0x0b72
0x000b8030: 0x0b72 0x0b65 0x0b6e 0x0b74 0x0b2d 0x0b63 0x0b76 0x0b73
0x000b8040: 0x0b20 0x0b30 0x0b35 0x0b20 0x0b4e 0x0b6f 0x0b76 0x0b20
0x000b8050: 0x0b32 0x0b30 0x0b30 0x0b33 0x0720 0x0720 0x0720 0x0720
0x000b8060: 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720
0x000b8070: 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720
0x000b8080: 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720
0x000b8090: 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720 0x0720
@end example
@end itemize
@item p or print/fmt expr
Print expression value. Only the @var{format} part of @var{fmt} is
used.
@c man begin AUTHOR
Fabrice Bellard
@c man end
@end table
@end ignore
@subsection Integer expressions
The monitor understands integers expressions for every integer
argument. You can use register names to get the value of specifics
CPU registers by prefixing them with @emph{$}.
@end ignore
@node disk_images
@section Disk Images
......@@ -649,13 +536,166 @@ Since holes are used, the displayed size of the COW disk image is not
the real one. To know it, use the @code{ls -ls} command.
@end enumerate
@section Direct Linux Boot and Network emulation
This section explains how to launch a Linux kernel inside QEMU without
having to make a full bootable image. It is very useful for fast Linux
kernel testing. The QEMU network configuration is also explained.
@enumerate
@item
Download the archive @file{linux-test-xxx.tar.gz} containing a Linux
kernel and a disk image.
@item Optional: If you want network support (for example to launch X11 examples), you
must copy the script @file{qemu-ifup} in @file{/etc} and configure
properly @code{sudo} so that the command @code{ifconfig} contained in
@file{qemu-ifup} can be executed as root. You must verify that your host
kernel supports the TUN/TAP network interfaces: the device
@file{/dev/net/tun} must be present.
When network is enabled, there is a virtual network connection between
the host kernel and the emulated kernel. The emulated kernel is seen
from the host kernel at IP address 172.20.0.2 and the host kernel is
seen from the emulated kernel at IP address 172.20.0.1.
@item Launch @code{qemu.sh}. You should have the following output:
@example
> ./qemu.sh
Connected to host network interface: tun0
Linux version 2.4.21 (bellard@voyager.localdomain) (gcc version 3.2.2 20030222 (Red Hat Linux 3.2.2-5)) #5 Tue Nov 11 18:18:53 CET 2003
BIOS-provided physical RAM map:
BIOS-e801: 0000000000000000 - 000000000009f000 (usable)
BIOS-e801: 0000000000100000 - 0000000002000000 (usable)
32MB LOWMEM available.
On node 0 totalpages: 8192
zone(0): 4096 pages.
zone(1): 4096 pages.
zone(2): 0 pages.
Kernel command line: root=/dev/hda sb=0x220,5,1,5 ide2=noprobe ide3=noprobe ide4=noprobe ide5=noprobe console=ttyS0
ide_setup: ide2=noprobe
ide_setup: ide3=noprobe
ide_setup: ide4=noprobe
ide_setup: ide5=noprobe
Initializing CPU#0
Detected 2399.621 MHz processor.
Console: colour EGA 80x25
Calibrating delay loop... 4744.80 BogoMIPS
Memory: 28872k/32768k available (1210k kernel code, 3508k reserved, 266k data, 64k init, 0k highmem)
Dentry cache hash table entries: 4096 (order: 3, 32768 bytes)
Inode cache hash table entries: 2048 (order: 2, 16384 bytes)
Mount cache hash table entries: 512 (order: 0, 4096 bytes)
Buffer-cache hash table entries: 1024 (order: 0, 4096 bytes)
Page-cache hash table entries: 8192 (order: 3, 32768 bytes)
CPU: Intel Pentium Pro stepping 03
Checking 'hlt' instruction... OK.
POSIX conformance testing by UNIFIX
Linux NET4.0 for Linux 2.4
Based upon Swansea University Computer Society NET3.039
Initializing RT netlink socket
apm: BIOS not found.
Starting kswapd
Journalled Block Device driver loaded
Detected PS/2 Mouse Port.
pty: 256 Unix98 ptys configured
Serial driver version 5.05c (2001-07-08) with no serial options enabled
ttyS00 at 0x03f8 (irq = 4) is a 16450
ne.c:v1.10 9/23/94 Donald Becker (becker@scyld.com)
Last modified Nov 1, 2000 by Paul Gortmaker
NE*000 ethercard probe at 0x300: 52 54 00 12 34 56
eth0: NE2000 found at 0x300, using IRQ 9.
RAMDISK driver initialized: 16 RAM disks of 4096K size 1024 blocksize
Uniform Multi-Platform E-IDE driver Revision: 7.00beta4-2.4
ide: Assuming 50MHz system bus speed for PIO modes; override with idebus=xx
hda: QEMU HARDDISK, ATA DISK drive
ide0 at 0x1f0-0x1f7,0x3f6 on irq 14
hda: attached ide-disk driver.
hda: 20480 sectors (10 MB) w/256KiB Cache, CHS=20/16/63
Partition check:
hda:
Soundblaster audio driver Copyright (C) by Hannu Savolainen 1993-1996
NET4: Linux TCP/IP 1.0 for NET4.0
IP Protocols: ICMP, UDP, TCP, IGMP
IP: routing cache hash table of 512 buckets, 4Kbytes
TCP: Hash tables configured (established 2048 bind 4096)
NET4: Unix domain sockets 1.0/SMP for Linux NET4.0.
EXT2-fs warning: mounting unchecked fs, running e2fsck is recommended
VFS: Mounted root (ext2 filesystem).
Freeing unused kernel memory: 64k freed
Linux version 2.4.21 (bellard@voyager.localdomain) (gcc version 3.2.2 20030222 (Red Hat Linux 3.2.2-5)) #5 Tue Nov 11 18:18:53 CET 2003
QEMU Linux test distribution (based on Redhat 9)
Type 'exit' to halt the system
sh-2.05b#
@end example
@item
Then you can play with the kernel inside the virtual serial console. You
can launch @code{ls} for example. Type @key{Ctrl-a h} to have an help
about the keys you can type inside the virtual serial console. In
particular, use @key{Ctrl-a x} to exit QEMU and use @key{Ctrl-a b} as
the Magic SysRq key.
@item
If the network is enabled, launch the script @file{/etc/linuxrc} in the
emulator (don't forget the leading dot):
@example
. /etc/linuxrc
@end example
Then enable X11 connections on your PC from the emulated Linux:
@example
xhost +172.20.0.2
@end example
You can now launch @file{xterm} or @file{xlogo} and verify that you have
a real Virtual Linux system !
@end enumerate
NOTES:
@enumerate
@item
A 2.5.74 kernel is also included in the archive. Just
replace the bzImage in qemu.sh to try it.
@item
qemu-fast creates a temporary file in @var{$QEMU_TMPDIR} (@file{/tmp} is the
default) containing all the simulated PC memory. If possible, try to use
a temporary directory using the tmpfs filesystem to avoid too many
unnecessary disk accesses.
@item
In order to exit cleanly from qemu, you can do a @emph{shutdown} inside
qemu. qemu will automatically exit when the Linux shutdown is done.
@item
You can boot slightly faster by disabling the probe of non present IDE
interfaces. To do so, add the following options on the kernel command
line:
@example
ide1=noprobe ide2=noprobe ide3=noprobe ide4=noprobe ide5=noprobe
@end example
@item
The example disk image is a modified version of the one made by Kevin
Lawton for the plex86 Project (@url{www.plex86.org}).
@end enumerate
@node linux_compile
@section Linux Kernel Compilation
You can use any linux kernel with QEMU. However, if you want to use
@code{qemu-fast} to get maximum performances, you should make the
following changes to the Linux kernel (only 2.4.x and 2.5.x were
tested):
@code{qemu-fast} to get maximum performances, you must use a modified
guest kernel. If you are using a 2.6 guest kernel, you can use
directly the patch @file{linux-2.6-qemu-fast.patch} made by Rusty
Russel available in the QEMU source archive. Otherwise, you can make the
following changes @emph{by hand} to the Linux kernel:
@enumerate
@item
......@@ -694,10 +734,10 @@ by
use an SMP kernel with QEMU, it only supports one CPU.
@item
If you are not using a 2.5 kernel as host kernel but if you use a target
2.5 kernel, you must also ensure that the 'HZ' define is set to 100
If you are not using a 2.6 kernel as host kernel but if you use a target
2.6 kernel, you must also ensure that the 'HZ' define is set to 100
(1000 is the default) as QEMU cannot currently emulate timers at
frequencies greater than 100 Hz on host Linux systems < 2.5. In
frequencies greater than 100 Hz on host Linux systems < 2.6. In
@file{include/asm/param.h}, replace:
@example
......@@ -762,322 +802,104 @@ Use @code{set architecture i8086} to dump 16 bit code. Then use
@code{x/10i $cs*16+*eip} to dump the code at the PC position.
@end enumerate
@chapter QEMU Internals
@section QEMU compared to other emulators
Like bochs [3], QEMU emulates an x86 CPU. But QEMU is much faster than
bochs as it uses dynamic compilation and because it uses the host MMU to
simulate the x86 MMU. The downside is that currently the emulation is
not as accurate as bochs (for example, you cannot currently run Windows
inside QEMU).
Like Valgrind [2], QEMU does user space emulation and dynamic
translation. Valgrind is mainly a memory debugger while QEMU has no
support for it (QEMU could be used to detect out of bound memory
accesses as Valgrind, but it has no support to track uninitialised data
as Valgrind does). The Valgrind dynamic translator generates better code
than QEMU (in particular it does register allocation) but it is closely
tied to an x86 host and target and has no support for precise exceptions
and system emulation.
EM86 [4] is the closest project to user space QEMU (and QEMU still uses
some of its code, in particular the ELF file loader). EM86 was limited
to an alpha host and used a proprietary and slow interpreter (the
interpreter part of the FX!32 Digital Win32 code translator [5]).
TWIN [6] is a Windows API emulator like Wine. It is less accurate than
Wine but includes a protected mode x86 interpreter to launch x86 Windows
executables. Such an approach as greater potential because most of the
Windows API is executed natively but it is far more difficult to develop
because all the data structures and function parameters exchanged
between the API and the x86 code must be converted.
User mode Linux [7] was the only solution before QEMU to launch a Linux
kernel as a process while not needing any host kernel patches. However,
user mode Linux requires heavy kernel patches while QEMU accepts
unpatched Linux kernels. It would be interesting to compare the
performance of the two approaches.
The new Plex86 [8] PC virtualizer is done in the same spirit as the QEMU
system emulator. It requires a patched Linux kernel to work (you cannot
launch the same kernel on your PC), but the patches are really small. As
it is a PC virtualizer (no emulation is done except for some priveledged
instructions), it has the potential of being faster than QEMU. The
downside is that a complicated (and potentially unsafe) host kernel
patch is needed.
@section Portable dynamic translation
QEMU is a dynamic translator. When it first encounters a piece of code,
it converts it to the host instruction set. Usually dynamic translators
are very complicated and highly CPU dependent. QEMU uses some tricks
which make it relatively easily portable and simple while achieving good
performances.
The basic idea is to split every x86 instruction into fewer simpler
instructions. Each simple instruction is implemented by a piece of C
code (see @file{op-i386.c}). Then a compile time tool (@file{dyngen})
takes the corresponding object file (@file{op-i386.o}) to generate a
dynamic code generator which concatenates the simple instructions to
build a function (see @file{op-i386.h:dyngen_code()}).
In essence, the process is similar to [1], but more work is done at
compile time.
A key idea to get optimal performances is that constant parameters can
be passed to the simple operations. For that purpose, dummy ELF
relocations are generated with gcc for each constant parameter. Then,
the tool (@file{dyngen}) can locate the relocations and generate the
appriopriate C code to resolve them when building the dynamic code.
That way, QEMU is no more difficult to port than a dynamic linker.
To go even faster, GCC static register variables are used to keep the
state of the virtual CPU.
@section Register allocation
Since QEMU uses fixed simple instructions, no efficient register
allocation can be done. However, because RISC CPUs have a lot of
register, most of the virtual CPU state can be put in registers without
doing complicated register allocation.
@section Condition code optimisations
Good CPU condition codes emulation (@code{EFLAGS} register on x86) is a
critical point to get good performances. QEMU uses lazy condition code
evaluation: instead of computing the condition codes after each x86
instruction, it just stores one operand (called @code{CC_SRC}), the
result (called @code{CC_DST}) and the type of operation (called
@code{CC_OP}).
@code{CC_OP} is almost never explicitely set in the generated code
because it is known at translation time.
In order to increase performances, a backward pass is performed on the
generated simple instructions (see
@code{translate-i386.c:optimize_flags()}). When it can be proved that
the condition codes are not needed by the next instructions, no
condition codes are computed at all.
@section CPU state optimisations
The x86 CPU has many internal states which change the way it evaluates
instructions. In order to achieve a good speed, the translation phase
considers that some state information of the virtual x86 CPU cannot
change in it. For example, if the SS, DS and ES segments have a zero
base, then the translator does not even generate an addition for the
segment base.
[The FPU stack pointer register is not handled that way yet].
@section Translation cache
A 2MByte cache holds the most recently used translations. For
simplicity, it is completely flushed when it is full. A translation unit
contains just a single basic block (a block of x86 instructions
terminated by a jump or by a virtual CPU state change which the
translator cannot deduce statically).
@section Direct block chaining
After each translated basic block is executed, QEMU uses the simulated
Program Counter (PC) and other cpu state informations (such as the CS
segment base value) to find the next basic block.
In order to accelerate the most common cases where the new simulated PC
is known, QEMU can patch a basic block so that it jumps directly to the
next one.
The most portable code uses an indirect jump. An indirect jump makes it
easier to make the jump target modification atomic. On some
architectures (such as PowerPC), the @code{JUMP} opcode is directly
patched so that the block chaining has no overhead.
@section Self-modifying code and translated code invalidation
Self-modifying code is a special challenge in x86 emulation because no
instruction cache invalidation is signaled by the application when code
is modified.
When translated code is generated for a basic block, the corresponding
host page is write protected if it is not already read-only (with the
system call @code{mprotect()}). Then, if a write access is done to the
page, Linux raises a SEGV signal. QEMU then invalidates all the
translated code in the page and enables write accesses to the page.
Correct translated code invalidation is done efficiently by maintaining
a linked list of every translated block contained in a given page. Other
linked lists are also maintained to undo direct block chaining.
Although the overhead of doing @code{mprotect()} calls is important,
most MSDOS programs can be emulated at reasonnable speed with QEMU and
DOSEMU.
Note that QEMU also invalidates pages of translated code when it detects
that memory mappings are modified with @code{mmap()} or @code{munmap()}.
@section Exception support
longjmp() is used when an exception such as division by zero is
encountered.
The host SIGSEGV and SIGBUS signal handlers are used to get invalid
memory accesses. The exact CPU state can be retrieved because all the
x86 registers are stored in fixed host registers. The simulated program
counter is found by retranslating the corresponding basic block and by
looking where the host program counter was at the exception point.
The virtual CPU cannot retrieve the exact @code{EFLAGS} register because
in some cases it is not computed because of condition code
optimisations. It is not a big concern because the emulated code can
still be restarted in any cases.
@section Linux system call translation
QEMU includes a generic system call translator for Linux. It means that
the parameters of the system calls can be converted to fix the
endianness and 32/64 bit issues. The IOCTLs are converted with a generic
type description system (see @file{ioctls.h} and @file{thunk.c}).
@chapter QEMU User space emulator invocation
QEMU supports host CPUs which have pages bigger than 4KB. It records all
the mappings the process does and try to emulated the @code{mmap()}
system calls in cases where the host @code{mmap()} call would fail
because of bad page alignment.
@section Quick Start
@section Linux signals
In order to launch a Linux process, QEMU needs the process executable
itself and all the target (x86) dynamic libraries used by it.
Normal and real-time signals are queued along with their information
(@code{siginfo_t}) as it is done in the Linux kernel. Then an interrupt
request is done to the virtual CPU. When it is interrupted, one queued
signal is handled by generating a stack frame in the virtual CPU as the
Linux kernel does. The @code{sigreturn()} system call is emulated to return
from the virtual signal handler.
@itemize
Some signals (such as SIGALRM) directly come from the host. Other
signals are synthetized from the virtual CPU exceptions such as SIGFPE
when a division by zero is done (see @code{main.c:cpu_loop()}).
@item On x86, you can just try to launch any process by using the native
libraries:
The blocked signal mask is still handled by the host Linux kernel so
that most signal system calls can be redirected directly to the host
Linux kernel. Only the @code{sigaction()} and @code{sigreturn()} system
calls need to be fully emulated (see @file{signal.c}).
@example
qemu-i386 -L / /bin/ls
@end example
@section clone() system call and threads
@code{-L /} tells that the x86 dynamic linker must be searched with a
@file{/} prefix.
The Linux clone() system call is usually used to create a thread. QEMU
uses the host clone() system call so that real host threads are created
for each emulated thread. One virtual CPU instance is created for each
thread.
@item Since QEMU is also a linux process, you can launch qemu with qemu (NOTE: you can only do that if you compiled QEMU from the sources):
The virtual x86 CPU atomic operations are emulated with a global lock so
that their semantic is preserved.
@example
qemu-i386 -L / qemu-i386 -L / /bin/ls
@end example
Note that currently there are still some locking issues in QEMU. In
particular, the translated cache flush is not protected yet against
reentrancy.
@item On non x86 CPUs, you need first to download at least an x86 glibc
(@file{qemu-runtime-i386-XXX-.tar.gz} on the QEMU web page). Ensure that
@code{LD_LIBRARY_PATH} is not set:
@section Self-virtualization
@example
unset LD_LIBRARY_PATH
@end example
QEMU was conceived so that ultimately it can emulate itself. Although
it is not very useful, it is an important test to show the power of the
emulator.
Then you can launch the precompiled @file{ls} x86 executable:
Achieving self-virtualization is not easy because there may be address
space conflicts. QEMU solves this problem by being an executable ELF
shared object as the ld-linux.so ELF interpreter. That way, it can be
relocated at load time.
@example
qemu-i386 tests/i386/ls
@end example
You can look at @file{qemu-binfmt-conf.sh} so that
QEMU is automatically launched by the Linux kernel when you try to
launch x86 executables. It requires the @code{binfmt_misc} module in the
Linux kernel.
@section MMU emulation
@item The x86 version of QEMU is also included. You can try weird things such as:
@example
qemu-i386 /usr/local/qemu-i386/bin/qemu-i386 /usr/local/qemu-i386/bin/ls-i386
@end example
For system emulation, QEMU uses the mmap() system call to emulate the
target CPU MMU. It works as long the emulated OS does not use an area
reserved by the host OS (such as the area above 0xc0000000 on x86
Linux).
@end itemize
It is planned to add a slower but more precise MMU emulation
with a software MMU.
@section Wine launch
@section Bibliography
@itemize
@table @asis
@item Ensure that you have a working QEMU with the x86 glibc
distribution (see previous section). In order to verify it, you must be
able to do:
@item [1]
@url{http://citeseer.nj.nec.com/piumarta98optimizing.html}, Optimizing
direct threaded code by selective inlining (1998) by Ian Piumarta, Fabio
Riccardi.
@example
qemu-i386 /usr/local/qemu-i386/bin/ls-i386
@end example
@item [2]
@url{http://developer.kde.org/~sewardj/}, Valgrind, an open-source
memory debugger for x86-GNU/Linux, by Julian Seward.
@item Download the binary x86 Wine install
(@file{qemu-XXX-i386-wine.tar.gz} on the QEMU web page).
@item [3]
@url{http://bochs.sourceforge.net/}, the Bochs IA-32 Emulator Project,
by Kevin Lawton et al.
@item Configure Wine on your account. Look at the provided script
@file{/usr/local/qemu-i386/bin/wine-conf.sh}. Your previous
@code{$@{HOME@}/.wine} directory is saved to @code{$@{HOME@}/.wine.org}.
@item [4]
@url{http://www.cs.rose-hulman.edu/~donaldlf/em86/index.html}, the EM86
x86 emulator on Alpha-Linux.
@item Then you can try the example @file{putty.exe}:
@item [5]
@url{http://www.usenix.org/publications/library/proceedings/usenix-nt97/full_papers/chernoff/chernoff.pdf},
DIGITAL FX!32: Running 32-Bit x86 Applications on Alpha NT, by Anton
Chernoff and Ray Hookway.
@example
qemu-i386 /usr/local/qemu-i386/wine/bin/wine /usr/local/qemu-i386/wine/c/Program\ Files/putty.exe
@end example
@item [6]
@url{http://www.willows.com/}, Windows API library emulation from
Willows Software.
@end itemize
@item [7]
@url{http://user-mode-linux.sourceforge.net/},
The User-mode Linux Kernel.
@section Command line options
@item [8]
@url{http://www.plex86.org/},
The new Plex86 project.
@example
usage: qemu-i386 [-h] [-d] [-L path] [-s size] program [arguments...]
@end example
@table @option
@item -h
Print the help
@item -L path
Set the x86 elf interpreter prefix (default=/usr/local/qemu-i386)
@item -s size
Set the x86 stack size in bytes (default=524288)
@end table
@chapter Regression Tests
In the directory @file{tests/}, various interesting testing programs
are available. There are used for regression testing.
@section @file{test-i386}
This program executes most of the 16 bit and 32 bit x86 instructions and
generates a text output. It can be compared with the output obtained with
a real CPU or another emulator. The target @code{make test} runs this
program and a @code{diff} on the generated output.
The Linux system call @code{modify_ldt()} is used to create x86 selectors
to test some 16 bit addressing and 32 bit with segmentation cases.
The Linux system call @code{vm86()} is used to test vm86 emulation.
Various exceptions are raised to test most of the x86 user space
exception reporting.
@section @file{linux-test}
This program tests various Linux system calls. It is used to verify
that the system call parameters are correctly converted between target
and host CPUs.
@section @file{hello-i386}
Very simple statically linked x86 program, just to test QEMU during a
port to a new host CPU.
@section @file{hello-arm}
Very simple statically linked ARM program, just to test QEMU during a
port to a new host CPU.
@section @file{sha1}
Debug options:
It is a simple benchmark. Care must be taken to interpret the results
because it mostly tests the ability of the virtual CPU to optimize the
@code{rol} x86 instruction and the condition code computations.
@table @option
@item -d
Activate log (logfile=/tmp/qemu.log)
@item -p pagesize
Act as if the host page size was 'pagesize' bytes
@end table
qemu-tech.texi 0 → 100644
浏览文件 @ 1f673135
\input texinfo @c -*- texinfo -*-
@iftex
@settitle QEMU Internals
@titlepage
@sp 7
@center @titlefont{QEMU Internals}
@sp 3
@end titlepage
@end iftex
@chapter Introduction
@section Features
QEMU is a FAST! processor emulator using a portable dynamic
translator.
QEMU has two operating modes:
@itemize @minus
@item
Full system emulation. In this mode, QEMU emulates a full system
(usually a PC), including a processor and various peripherials. It can
be used to launch an different Operating System without rebooting the
PC or to debug system code.
@item
User mode emulation (Linux host only). In this mode, QEMU can launch
Linux processes compiled for one CPU on another CPU. It can be used to
launch the Wine Windows API emulator (@url{http://www.winehq.org}) or
to ease cross-compilation and cross-debugging.
@end itemize
As QEMU requires no host kernel driver to run, it is very safe and
easy to use.
QEMU generic features:
@itemize
@item User space only or full system emulation.
@item Using dynamic translation to native code for reasonnable speed.
@item Working on x86 and PowerPC hosts. Being tested on ARM, Sparc32, Alpha and S390.
@item Self-modifying code support.
@item Precise exceptions support.
@item The virtual CPU is a library (@code{libqemu}) which can be used
in other projects.
@end itemize
QEMU user mode emulation features:
@itemize
@item Generic Linux system call converter, including most ioctls.
@item clone() emulation using native CPU clone() to use Linux scheduler for threads.
@item Accurate signal handling by remapping host signals to target signals.
@end itemize
@end itemize
QEMU full system emulation features:
@itemize
@item QEMU can either use a full software MMU for maximum portability or use the host system call mmap() to simulate the target MMU.
@end itemize
@section x86 emulation
QEMU x86 target features:
@itemize
@item The virtual x86 CPU supports 16 bit and 32 bit addressing with segmentation.
LDT/GDT and IDT are emulated. VM86 mode is also supported to run DOSEMU.
@item Support of host page sizes bigger than 4KB in user mode emulation.
@item QEMU can emulate itself on x86.
@item An extensive Linux x86 CPU test program is included @file{tests/test-i386}.
It can be used to test other x86 virtual CPUs.
@end itemize
Current QEMU limitations:
@itemize
@item No SSE/MMX support (yet).
@item No x86-64 support.
@item IPC syscalls are missing.
@item The x86 segment limits and access rights are not tested at every
memory access (yet). Hopefully, very few OSes seem to rely on that for
normal use.
@item On non x86 host CPUs, @code{double}s are used instead of the non standard
10 byte @code{long double}s of x86 for floating point emulation to get
maximum performances.
@end itemize
@section ARM emulation
@itemize
@item Full ARM 7 user emulation.
@item NWFPE FPU support included in user Linux emulation.
@item Can run most ARM Linux binaries.
@end itemize
@section PowerPC emulation
@itemize
@item Full PowerPC 32 bit emulation, including priviledged instructions,
FPU and MMU.
@item Can run most PowerPC Linux binaries.
@end itemize
@section SPARC emulation
@itemize
@item SPARC V8 user support, except FPU instructions.
@item Can run some SPARC Linux binaries.
@end itemize
@chapter QEMU Internals
@section QEMU compared to other emulators
Like bochs [3], QEMU emulates an x86 CPU. But QEMU is much faster than
bochs as it uses dynamic compilation. Bochs is closely tied to x86 PC
emulation while QEMU can emulate several processors.
Like Valgrind [2], QEMU does user space emulation and dynamic
translation. Valgrind is mainly a memory debugger while QEMU has no
support for it (QEMU could be used to detect out of bound memory
accesses as Valgrind, but it has no support to track uninitialised data
as Valgrind does). The Valgrind dynamic translator generates better code
than QEMU (in particular it does register allocation) but it is closely
tied to an x86 host and target and has no support for precise exceptions
and system emulation.
EM86 [4] is the closest project to user space QEMU (and QEMU still uses
some of its code, in particular the ELF file loader). EM86 was limited
to an alpha host and used a proprietary and slow interpreter (the
interpreter part of the FX!32 Digital Win32 code translator [5]).
TWIN [6] is a Windows API emulator like Wine. It is less accurate than
Wine but includes a protected mode x86 interpreter to launch x86 Windows
executables. Such an approach as greater potential because most of the
Windows API is executed natively but it is far more difficult to develop
because all the data structures and function parameters exchanged
between the API and the x86 code must be converted.
User mode Linux [7] was the only solution before QEMU to launch a
Linux kernel as a process while not needing any host kernel
patches. However, user mode Linux requires heavy kernel patches while
QEMU accepts unpatched Linux kernels. The price to pay is that QEMU is
slower.
The new Plex86 [8] PC virtualizer is done in the same spirit as the
qemu-fast system emulator. It requires a patched Linux kernel to work
(you cannot launch the same kernel on your PC), but the patches are
really small. As it is a PC virtualizer (no emulation is done except
for some priveledged instructions), it has the potential of being
faster than QEMU. The downside is that a complicated (and potentially
unsafe) host kernel patch is needed.
The commercial PC Virtualizers (VMWare [9], VirtualPC [10], TwoOStwo
[11]) are faster than QEMU, but they all need specific, proprietary
and potentially unsafe host drivers. Moreover, they are unable to
provide cycle exact simulation as an emulator can.
@section Portable dynamic translation
QEMU is a dynamic translator. When it first encounters a piece of code,
it converts it to the host instruction set. Usually dynamic translators
are very complicated and highly CPU dependent. QEMU uses some tricks
which make it relatively easily portable and simple while achieving good
performances.
The basic idea is to split every x86 instruction into fewer simpler
instructions. Each simple instruction is implemented by a piece of C
code (see @file{target-i386/op.c}). Then a compile time tool
(@file{dyngen}) takes the corresponding object file (@file{op.o})
to generate a dynamic code generator which concatenates the simple
instructions to build a function (see @file{op.h:dyngen_code()}).
In essence, the process is similar to [1], but more work is done at
compile time.
A key idea to get optimal performances is that constant parameters can
be passed to the simple operations. For that purpose, dummy ELF
relocations are generated with gcc for each constant parameter. Then,
the tool (@file{dyngen}) can locate the relocations and generate the
appriopriate C code to resolve them when building the dynamic code.
That way, QEMU is no more difficult to port than a dynamic linker.
To go even faster, GCC static register variables are used to keep the
state of the virtual CPU.
@section Register allocation
Since QEMU uses fixed simple instructions, no efficient register
allocation can be done. However, because RISC CPUs have a lot of
register, most of the virtual CPU state can be put in registers without
doing complicated register allocation.
@section Condition code optimisations
Good CPU condition codes emulation (@code{EFLAGS} register on x86) is a
critical point to get good performances. QEMU uses lazy condition code
evaluation: instead of computing the condition codes after each x86
instruction, it just stores one operand (called @code{CC_SRC}), the
result (called @code{CC_DST}) and the type of operation (called
@code{CC_OP}).
@code{CC_OP} is almost never explicitely set in the generated code
because it is known at translation time.
In order to increase performances, a backward pass is performed on the
generated simple instructions (see
@code{target-i386/translate.c:optimize_flags()}). When it can be proved that
the condition codes are not needed by the next instructions, no
condition codes are computed at all.
@section CPU state optimisations
The x86 CPU has many internal states which change the way it evaluates
instructions. In order to achieve a good speed, the translation phase
considers that some state information of the virtual x86 CPU cannot
change in it. For example, if the SS, DS and ES segments have a zero
base, then the translator does not even generate an addition for the
segment base.
[The FPU stack pointer register is not handled that way yet].
@section Translation cache
A 2MByte cache holds the most recently used translations. For
simplicity, it is completely flushed when it is full. A translation unit
contains just a single basic block (a block of x86 instructions
terminated by a jump or by a virtual CPU state change which the
translator cannot deduce statically).
@section Direct block chaining
After each translated basic block is executed, QEMU uses the simulated
Program Counter (PC) and other cpu state informations (such as the CS
segment base value) to find the next basic block.
In order to accelerate the most common cases where the new simulated PC
is known, QEMU can patch a basic block so that it jumps directly to the
next one.
The most portable code uses an indirect jump. An indirect jump makes
it easier to make the jump target modification atomic. On some host
architectures (such as x86 or PowerPC), the @code{JUMP} opcode is
directly patched so that the block chaining has no overhead.
@section Self-modifying code and translated code invalidation
Self-modifying code is a special challenge in x86 emulation because no
instruction cache invalidation is signaled by the application when code
is modified.
When translated code is generated for a basic block, the corresponding
host page is write protected if it is not already read-only (with the
system call @code{mprotect()}). Then, if a write access is done to the
page, Linux raises a SEGV signal. QEMU then invalidates all the
translated code in the page and enables write accesses to the page.
Correct translated code invalidation is done efficiently by maintaining
a linked list of every translated block contained in a given page. Other
linked lists are also maintained to undo direct block chaining.
Although the overhead of doing @code{mprotect()} calls is important,
most MSDOS programs can be emulated at reasonnable speed with QEMU and
DOSEMU.
Note that QEMU also invalidates pages of translated code when it detects
that memory mappings are modified with @code{mmap()} or @code{munmap()}.
When using a software MMU, the code invalidation is more efficient: if
a given code page is invalidated too often because of write accesses,
then a bitmap representing all the code inside the page is
built. Every store into that page checks the bitmap to see if the code
really needs to be invalidated. It avoids invalidating the code when
only data is modified in the page.
@section Exception support
longjmp() is used when an exception such as division by zero is
encountered.
The host SIGSEGV and SIGBUS signal handlers are used to get invalid
memory accesses. The exact CPU state can be retrieved because all the
x86 registers are stored in fixed host registers. The simulated program
counter is found by retranslating the corresponding basic block and by
looking where the host program counter was at the exception point.
The virtual CPU cannot retrieve the exact @code{EFLAGS} register because
in some cases it is not computed because of condition code
optimisations. It is not a big concern because the emulated code can
still be restarted in any cases.
@section MMU emulation
For system emulation, QEMU uses the mmap() system call to emulate the
target CPU MMU. It works as long the emulated OS does not use an area
reserved by the host OS (such as the area above 0xc0000000 on x86
Linux).
In order to be able to launch any OS, QEMU also supports a soft
MMU. In that mode, the MMU virtual to physical address translation is
done at every memory access. QEMU uses an address translation cache to
speed up the translation.
In order to avoid flushing the translated code each time the MMU
mappings change, QEMU uses a physically indexed translation cache. It
means that each basic block is indexed with its physical address.
When MMU mappings change, only the chaining of the basic blocks is
reset (i.e. a basic block can no longer jump directly to another one).
@section Hardware interrupts
In order to be faster, QEMU does not check at every basic block if an
hardware interrupt is pending. Instead, the user must asynchrously
call a specific function to tell that an interrupt is pending. This
function resets the chaining of the currently executing basic
block. It ensures that the execution will return soon in the main loop
of the CPU emulator. Then the main loop can test if the interrupt is
pending and handle it.
@section User emulation specific details
@subsection Linux system call translation
QEMU includes a generic system call translator for Linux. It means that
the parameters of the system calls can be converted to fix the
endianness and 32/64 bit issues. The IOCTLs are converted with a generic
type description system (see @file{ioctls.h} and @file{thunk.c}).
QEMU supports host CPUs which have pages bigger than 4KB. It records all
the mappings the process does and try to emulated the @code{mmap()}
system calls in cases where the host @code{mmap()} call would fail
because of bad page alignment.
@subsection Linux signals
Normal and real-time signals are queued along with their information
(@code{siginfo_t}) as it is done in the Linux kernel. Then an interrupt
request is done to the virtual CPU. When it is interrupted, one queued
signal is handled by generating a stack frame in the virtual CPU as the
Linux kernel does. The @code{sigreturn()} system call is emulated to return
from the virtual signal handler.
Some signals (such as SIGALRM) directly come from the host. Other
signals are synthetized from the virtual CPU exceptions such as SIGFPE
when a division by zero is done (see @code{main.c:cpu_loop()}).
The blocked signal mask is still handled by the host Linux kernel so
that most signal system calls can be redirected directly to the host
Linux kernel. Only the @code{sigaction()} and @code{sigreturn()} system
calls need to be fully emulated (see @file{signal.c}).
@subsection clone() system call and threads
The Linux clone() system call is usually used to create a thread. QEMU
uses the host clone() system call so that real host threads are created
for each emulated thread. One virtual CPU instance is created for each
thread.
The virtual x86 CPU atomic operations are emulated with a global lock so
that their semantic is preserved.
Note that currently there are still some locking issues in QEMU. In
particular, the translated cache flush is not protected yet against
reentrancy.
@subsection Self-virtualization
QEMU was conceived so that ultimately it can emulate itself. Although
it is not very useful, it is an important test to show the power of the
emulator.
Achieving self-virtualization is not easy because there may be address
space conflicts. QEMU solves this problem by being an executable ELF
shared object as the ld-linux.so ELF interpreter. That way, it can be
relocated at load time.
@section Bibliography
@table @asis
@item [1]
@url{http://citeseer.nj.nec.com/piumarta98optimizing.html}, Optimizing
direct threaded code by selective inlining (1998) by Ian Piumarta, Fabio
Riccardi.
@item [2]
@url{http://developer.kde.org/~sewardj/}, Valgrind, an open-source
memory debugger for x86-GNU/Linux, by Julian Seward.
@item [3]
@url{http://bochs.sourceforge.net/}, the Bochs IA-32 Emulator Project,
by Kevin Lawton et al.
@item [4]
@url{http://www.cs.rose-hulman.edu/~donaldlf/em86/index.html}, the EM86
x86 emulator on Alpha-Linux.
@item [5]
@url{http://www.usenix.org/publications/library/proceedings/usenix-nt97/full_papers/chernoff/chernoff.pdf},
DIGITAL FX!32: Running 32-Bit x86 Applications on Alpha NT, by Anton
Chernoff and Ray Hookway.
@item [6]
@url{http://www.willows.com/}, Windows API library emulation from
Willows Software.
@item [7]
@url{http://user-mode-linux.sourceforge.net/},
The User-mode Linux Kernel.
@item [8]
@url{http://www.plex86.org/},
The new Plex86 project.
@item [9]
@url{http://www.vmware.com/},
The VMWare PC virtualizer.
@item [10]
@url{http://www.microsoft.com/windowsxp/virtualpc/},
The VirtualPC PC virtualizer.
@item [11]
@url{http://www.twoostwo.org/},
The TwoOStwo PC virtualizer.
@end table
@chapter Regression Tests
In the directory @file{tests/}, various interesting testing programs
are available. There are used for regression testing.
@section @file{test-i386}
This program executes most of the 16 bit and 32 bit x86 instructions and
generates a text output. It can be compared with the output obtained with
a real CPU or another emulator. The target @code{make test} runs this
program and a @code{diff} on the generated output.
The Linux system call @code{modify_ldt()} is used to create x86 selectors
to test some 16 bit addressing and 32 bit with segmentation cases.
The Linux system call @code{vm86()} is used to test vm86 emulation.
Various exceptions are raised to test most of the x86 user space
exception reporting.
@section @file{linux-test}
This program tests various Linux system calls. It is used to verify
that the system call parameters are correctly converted between target
and host CPUs.
@section @file{hello-i386}
Very simple statically linked x86 program, just to test QEMU during a
port to a new host CPU.
@section @file{hello-arm}
Very simple statically linked ARM program, just to test QEMU during a
port to a new host CPU.
@section @file{sha1}
It is a simple benchmark. Care must be taken to interpret the results
because it mostly tests the ability of the virtual CPU to optimize the
@code{rol} x86 instruction and the condition code computations.
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