Re: [Qemu-devel] [PATCH] fix linuxboot.bin and multiboot.bin to not hijack int19

[Anthony Liguori]

On 01/31/2011 03:02 AM, Gleb Natapov wrote:
> Currently linuxboot.bin and multiboot.bin option roms override int19
> vector to intercept boot process. No sane option rom should do that.
> Provide bev entry instead that will be called by BIOS if option rom
> is selected for booting.
>
> Signed-off-by: Gleb Natapov<address@hidden>
> ---
>
> Note that this patch should be applied after qemu will upgrade to Seabios
> that supports boot order. Otherwise there will be change in behavior
> since option rom will not be selected for booting by default.
>    

I don't think there's a SeaBIOS release yet that includes the boot order 
support.

Regards,

Anthony Liguori

> diff --git a/pc-bios/optionrom/linuxboot.S b/pc-bios/optionrom/linuxboot.S
> index c109363..79b3ae8 100644
> --- a/pc-bios/optionrom/linuxboot.S
> +++ b/pc-bios/optionrom/linuxboot.S
> @@ -22,6 +22,8 @@
>
>   #include "optionrom.h"
>
> +#define PRODUCT "Linux loader"
> +
>   BOOT_ROM_START
>
>   run_linuxboot:
> diff --git a/pc-bios/optionrom/multiboot.S b/pc-bios/optionrom/multiboot.S
> index 9131837..069c4e8 100644
> --- a/pc-bios/optionrom/multiboot.S
> +++ b/pc-bios/optionrom/multiboot.S
> @@ -20,6 +20,8 @@
>
>   #include "optionrom.h"
>
> +#define PRODUCT "multiboot loader"
> +
>   #define MULTIBOOT_MAGIC               0x2badb002
>
>   #define GS_PROT_JUMP          0
> diff --git a/pc-bios/optionrom/optionrom.h b/pc-bios/optionrom/optionrom.h
> index fbdd48a..95dbdda 100644
> --- a/pc-bios/optionrom/optionrom.h
> +++ b/pc-bios/optionrom/optionrom.h
> @@ -93,31 +93,41 @@
>         .global         _start;                         \
>       _start:;                                          \
>         .short          0xaa55;                         \
> -       .byte           (_end - _start) / 512;
> +       .byte           (_end - _start) / 512;          \
> +       lret;                                           \
> +       .org            0x18;                           \
> +       .short          0;                              \
> +       .short          _pnph;                          \
> +    _pnph:                                             \
> +       .ascii          "$PnP";                               \
> +       .byte           0x01;                           \
> +       .byte           ( _pnph_len / 16 );             \
> +       .short          0x0000;                         \
> +       .byte           0x00;                           \
> +       .byte           0x00;                           \
> +       .long           0x00000000;                     \
> +       .short          _manufacturer;                  \
> +       .short          _product;                       \
> +       .long           0x00000000;                     \
> +       .short          0x0000;                         \
> +       .short          0x0000;                         \
> +       .short          _bev;                           \
> +       .short          0x0000;                         \
> +       .short          0x0000;                         \
> +       .equ            _pnph_len, . - _pnph;
>
>   #define BOOT_ROM_START                                        \
>         OPTION_ROM_START                                \
> -       push            %eax;                           \
> -       push            %ds;                            \
> -                                                       \
> -       /* setup ds so we can access the IVT */         \
> -       xor             %ax, %ax;                       \
> -       mov             %ax, %ds;                       \
> -                                                       \
> -       /* install our int 19 handler */                \
> -       movw            $int19_handler, (0x19*4);       \
> -       mov             %cs, (0x19*4+2);                \
> -                                                       \
> -       pop             %ds;                            \
> -       pop             %eax;                           \
> -       lret;                                           \
> -                                                       \
> -    int19_handler:;                                    \
> +    _bev:;                                             \
>         /* DS = CS */                                   \
>         movw            %cs, %ax;                       \
>         movw            %ax, %ds;
>
>   #define OPTION_ROM_END                                        \
> +    _manufacturer:;                                    \
> +        .asciz "QEMU";                                       \
> +    _product:;                                         \
> +        .asciz PRODUCT;                                        \
>       .align 512, 0;                                    \
>       _end:
>
> --
>                         Gleb.
>
>