This is a postcopy test (x86 only) that actually runs the guest
and checks the memory contents.

The test runs from an x86 boot block with the hex embedded in the test;
the source for this is:

...........

.code16
.org 0x7c00
	.file	"fill.s"
	.text
	.globl	start
	.type	start, @function
start:             # at 0x7c00 ?
        cli
        lgdt gdtdesc
        mov $1,%eax
        mov %eax,%cr0  # Protected mode enable
        data32 ljmp $8,$0x7c20

.org 0x7c20
.code32
        # A20 enable - not sure I actually need this
        inb $0x92,%al
        or  $2,%al
        outb %al, $0x92

        # set up DS for the whole of RAM (needed on KVM)
        mov $16,%eax
        mov %eax,%ds

        mov $65,%ax
        mov $0x3f8,%dx
        outb %al,%dx

        # bl keeps a counter so we limit the output speed
        mov $0, %bl
mainloop:
        # Start from 1MB
        mov $(1024*1024),%eax
innerloop:
        incb (%eax)
        add $4096,%eax
        cmp $(100*1024*1024),%eax
        jl innerloop

        inc %bl
        jnz mainloop

        mov $66,%ax
        mov $0x3f8,%dx
        outb %al,%dx

	jmp mainloop

        # GDT magic from old (GPLv2)  Grub startup.S
        .p2align        2       /* force 4-byte alignment */
gdt:
        .word   0, 0
        .byte   0, 0, 0, 0

        /* -- code segment --
         * base = 0x00000000, limit = 0xFFFFF (4 KiB Granularity), present
         * type = 32bit code execute/read, DPL = 0
         */
        .word   0xFFFF, 0
        .byte   0, 0x9A, 0xCF, 0

        /* -- data segment --
         * base = 0x00000000, limit 0xFFFFF (4 KiB Granularity), present
         * type = 32 bit data read/write, DPL = 0
         */
        .word   0xFFFF, 0
        .byte   0, 0x92, 0xCF, 0

gdtdesc:
        .word   0x27                    /* limit */
        .long   gdt                     /* addr */

/* I'm a bootable disk */
.org 0x7dfe
        .byte 0x55
        .byte 0xAA

...........

and that can be assembled by the following magic:
    as --32 -march=i486 fill.s -o fill.o
    objcopy -O binary fill.o fill.boot
    dd if=fill.boot of=bootsect bs=256 count=2 skip=124
    xxd -i bootsect
Signed-off-by: NDr. David Alan Gilbert <dgilbert@redhat.com>
Reviewed-by: NMarcel Apfelbaum <marcel@redhat.com>
Message-id: 1465816605-29488-5-git-send-email-dgilbert@redhat.com
Message-Id: <1465816605-29488-5-git-send-email-dgilbert@redhat.com>
Signed-off-by: NAmit Shah <amit.shah@redhat.com>