add a boot parameter to set reboot timeout

Added an option to let qemu transfer a configuration file to bios,
"etc/boot-fail-wait", which could be specified by command
    -boot reboot-timeout=T
T have a max value of 0xffff, unit is ms.

With this option, guest will wait for a given time if not find
bootabled device, then reboot. If reboot-timeout is '-1', guest
will not reboot, qemu passes '-1' to bios by default.

This feature need the new seabios's support.

Seabios pulls the value from the fwcfg "file" interface, this
interface is used because SeaBIOS needs a reliable way of
obtaining a name, value size, and value. It in no way requires
that there be a real file on the user's host machine.
Signed-off-by: NAmos Kong <akong@redhat.com>
Signed-off-by: NAnthony Liguori <aliguori@us.ibm.com>

hw/fw_cfg.c

@@ -183,6 +183,30 @@ static void fw_cfg_bootsplash(FWCfgState *s)
     }
 }
 
+static void fw_cfg_reboot(FWCfgState *s)
+{
+    int reboot_timeout = -1;
+    char *p;
+    const char *temp;
+
+    /* get user configuration */
+    QemuOptsList *plist = qemu_find_opts("boot-opts");
+    QemuOpts *opts = QTAILQ_FIRST(&plist->head);
+    if (opts != NULL) {
+        temp = qemu_opt_get(opts, "reboot-timeout");
+        if (temp != NULL) {
+            p = (char *)temp;
+            reboot_timeout = strtol(p, (char **)&p, 10);
+        }
+    }
+    /* validate the input */
+    if (reboot_timeout > 0xffff) {
+        error_report("reboot timeout is larger than 65535, force it to 65535.");
+        reboot_timeout = 0xffff;
+    }
+    fw_cfg_add_file(s, "etc/boot-fail-wait", g_memdup(&reboot_timeout, 4), 4);
+}
+
 static void fw_cfg_write(FWCfgState *s, uint8_t value)
 {
     int arch = !!(s->cur_entry & FW_CFG_ARCH_LOCAL);
@@ -497,6 +521,7 @@ FWCfgState *fw_cfg_init(uint32_t ctl_port, uint32_t data_port,
     fw_cfg_add_i16(s, FW_CFG_MAX_CPUS, (uint16_t)max_cpus);
     fw_cfg_add_i16(s, FW_CFG_BOOT_MENU, (uint16_t)boot_menu);
     fw_cfg_bootsplash(s);
+    fw_cfg_reboot(s);
 
     s->machine_ready.notify = fw_cfg_machine_ready;
     qemu_add_machine_init_done_notifier(&s->machine_ready);

qemu-config.c

@@ -645,6 +645,9 @@ QemuOptsList qemu_boot_opts = {
         }, {
             .name = "splash-time",
             .type = QEMU_OPT_STRING,
+        }, {
+            .name = "reboot-timeout",
+            .type = QEMU_OPT_STRING,
         },
         { /*End of list */ }
     },

qemu-options.hx

@@ -344,13 +344,14 @@ ETEXI
 
 DEF("boot", HAS_ARG, QEMU_OPTION_boot,
     "-boot [order=drives][,once=drives][,menu=on|off]\n"
-    "      [,splash=sp_name][,splash-time=sp_time]\n"
+    "      [,splash=sp_name][,splash-time=sp_time][,reboot-timeout=rb_time]\n"
     "                'drives': floppy (a), hard disk (c), CD-ROM (d), network (n)\n"
     "                'sp_name': the file's name that would be passed to bios as logo picture, if menu=on\n"
-    "                'sp_time': the period that splash picture last if menu=on, unit is ms\n",
+    "                'sp_time': the period that splash picture last if menu=on, unit is ms\n"
+    "                'rb_timeout': the timeout before guest reboot when boot failed, unit is ms\n",
     QEMU_ARCH_ALL)
 STEXI
-@item -boot [order=@var{drives}][,once=@var{drives}][,menu=on|off][,splash=@var{sp_name}][,splash-time=@var{sp_time}]
+@item -boot [order=@var{drives}][,once=@var{drives}][,menu=on|off][,splash=@var{sp_name}][,splash-time=@var{sp_time}][,reboot-timeout=@var{rb_timeout}]
 @findex -boot
 Specify boot order @var{drives} as a string of drive letters. Valid
 drive letters depend on the target achitecture. The x86 PC uses: a, b
@@ -369,6 +370,11 @@ limitation: The splash file could be a jpeg file or a BMP file in 24 BPP
 format(true color). The resolution should be supported by the SVGA mode, so
 the recommended is 320x240, 640x480, 800x640.
 
+A timeout could be passed to bios, guest will pause for @var{rb_timeout} ms
+when boot failed, then reboot. If @var{rb_timeout} is '-1', guest will not
+reboot, qemu passes '-1' to bios by default. Currently Seabios for X86
+system support it.
+
 @example
 # try to boot from network first, then from hard disk
 qemu-system-i386 -boot order=nc

vl.c

@@ -2632,7 +2632,8 @@ int main(int argc, char **argv, char **envp)
                 {
                     static const char * const params[] = {
                         "order", "once", "menu",
-                        "splash", "splash-time", NULL
+                        "splash", "splash-time",
+                        "reboot-timeout", NULL
                     };
                     char buf[sizeof(boot_devices)];
                     char *standard_boot_devices;