Re: [Patch] [BIOS] support BCV for rombios

["Sebastian Herbszt" <herbszt@gmx.de>]

Akio Takebe wrote:
> Hi,
> 
> This patch supports BCV for PCI device.
> If we use this patch in Xen, we would need some more fixes.
> This patch just support BCV.
> We could boot a full virtualize guest from a Pass through device
> with VT-d on Xen.
> 
> Signed-off-by: Akio Takebe <takebe_akio@jp.fujitsu.com>
> Signed-off-by: Kouya Shimura <kouya@jp.fujitsu.com>
> 
> Ref:
> - XenSummit Asia 2008
>  http://www.xen.org/files/xensummit_tokyo/24_Hitoshi%20Matsumoto_en.pdf
> - BIOS Boot Specification
>  http://www.phoenix.com/NR/rdonlyres/56E38DE2-3E6F-4743-835F-B4A53726ABED/0/specsbbs101.pdf
> 
> Best Regards,
> 
> Akio Takebe
> 
> Index: rombios.c
> ===================================================================
> RCS file: /cvsroot/bochs/bochs/bios/rombios.c,v
> retrieving revision 1.209
> diff -c -r1.209 rombios.c
> *** rombios.c 2 Jun 2008 20:08:10 -0000 1.209
> --- rombios.c 8 Dec 2008 10:09:53 -0000
> ***************
> *** 10194,10199 ****
> --- 10194,10223 ----
>     mov  ax, 2[bx]
>     cmp  ax, #0x506e
>     jne  no_bev
> + 
> +   mov  ax, 0x16[bx] ;; 0x16 is the offset of Boot Connection Vector
> +   cmp  ax, #0x0000
> +   je   no_bcv
> + 
> +   ;; Option ROM has BCV. Run it now.
> +   push cx       ;; Push seg
> +   push ax       ;; Push offset
> + 
> +   ;; Point ES:DI at "$PnP", which tells the ROM that we are a PnP BIOS.
> +   mov  bx, #0xf000
> +   mov  es, bx
> +   lea  di, pnp_string

Should ax, bx and dx get set to some sane value, e.g. 0? Those are only needed
for PnP ISA devices, but some broken option rom might expect something there.

> +   /* jump to BCV function entry pointer */
> +   mov  bp, sp   ;; Call ROM BCV routine using seg:off on stack
> +   db   0xff     ;; call_far ss:[bp+0]
> +   db   0x5e
> +   db   0
> +   cli           ;; In case expansion ROM BIOS turns IF on
> +   add  sp, #2   ;; Pop offset value
> +   pop  cx       ;; Pop seg value (restore CX)
> +   ja   no_bev

ja? not jmp?

> + no_bcv:
>     mov  ax, 0x1a[bx] ;; 0x1A is also the offset into the expansion header of...
>     cmp  ax, #0x0000  ;; the Bootstrap Entry Vector, or zero if there is none.
>     je   no_bev

- Sebastian


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