Re: [Qemu-devel] [PATCH v3 05/16] pc: Make -no-fd-bootchk stick across boot order changes

[Anthony Liguori <aliguori@us.ibm.com>]

Markus Armbruster <armbru@redhat.com> writes:

> Option -no-fd-bootchk asks the BIOS to attempt booting from a floppy
> even when the boot sector signature isn't there, by setting a bit in
> RTC CMOS.  It was added back in 2006 (commit 52ca8d6a).
>
> Two years later, commit 0ecdffbb added monitor command boot_set.
> Implemented by new function pc_boot_set().  It unconditionally clears
> the floppy signature bit in CMOS.
>
> Commit e0f084bf added -boot option once to automatically change the
> boot order on first reset.  Reuses pc_boot_set(), thus also clears the
> floppy signature bit.  Commit d9346e81 took care to preserve this
> behavior.

Quite a history there :-)

Does anyone still use no-fd-bootchk?  Do you know what the original
use-case was?

> Thus, -no-fd-bootchk applies to any number of boots.  Except it
> applies just to the first boot with -boot once, and never after
> boot_set.  Weird.  Make it stick instead: set the bit according to
> -no-fd-bootchk in pc_boot_set().
>
> Signed-off-by: Markus Armbruster <armbru@redhat.com>

Reviewed-by: Anthony Liguori <aliguori@us.ibm.com>

Regards,

Anthony Liguori

> ---
>  hw/i386/pc.c | 7 +++----
>  1 file changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
> index 4844a6b..7e524fc 100644
> --- a/hw/i386/pc.c
> +++ b/hw/i386/pc.c
> @@ -266,7 +266,7 @@ static int boot_device2nibble(char boot_device)
>      return 0;
>  }
>  
> -static int set_boot_dev(ISADevice *s, const char *boot_device, int fd_bootchk)
> +static int set_boot_dev(ISADevice *s, const char *boot_device)
>  {
>  #define PC_MAX_BOOT_DEVICES 3
>      int nbds, bds[3] = { 0, };
> @@ -292,7 +292,7 @@ static int set_boot_dev(ISADevice *s, const char *boot_device, int fd_bootchk)
>  
>  static int pc_boot_set(void *opaque, const char *boot_device)
>  {
> -    return set_boot_dev(opaque, boot_device, 0);
> +    return set_boot_dev(opaque, boot_device);
>  }
>  
>  typedef struct pc_cmos_init_late_arg {
> @@ -407,8 +407,7 @@ void pc_cmos_init(ram_addr_t ram_size, ram_addr_t above_4g_mem_size,
>      cpu_hotplug_cb.cpu_added_notifier.notify = rtc_notify_cpu_added;
>      qemu_register_cpu_added_notifier(&cpu_hotplug_cb.cpu_added_notifier);
>  
> -    /* set boot devices, and disable floppy signature check if requested */
> -    if (set_boot_dev(s, boot_device, fd_bootchk)) {
> +    if (set_boot_dev(s, boot_device)) {
>          exit(1);
>      }
>  
> -- 
> 1.7.11.7