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

[Anthony Liguori <anthony@codemonkey.ws>]

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<gleb@redhat.com>
> ---
>
> 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.
>
>