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

[Alexander Graf]

On 31.01.2011, at 10:02, 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.
> 
> 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";                         \

The idea behind the OPTION_ROM and BOOT_ROM split was to have a generic header 
that can be used as template for random option roms or boot roms alike. Your 
patch munges those two use-cases together by providing bev logic in the generic 
option rom part.

Please split it out into the BOOT_ROM macro, or - if necessary - create a new 
macro.


Alex