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From: Fabrice Bellard <fabrice@bellard.org>
To: samuel.thibault@ens-lyon.org
Cc: guillem@debian.org, qemu-devel@nongnu.org
Subject: Re: [Qemu-devel] PCI Bios fixup
Date: Sat, 09 Sep 2006 14:10:01 +0200	[thread overview]
Message-ID: <4502AF19.6050002@bellard.org> (raw)
In-Reply-To: <20060907010229.GF6876@bouh.residence.ens-lyon.fr>

Right, this is better. An even better fix would be to clear CS.RPL 
before the popf.

Regards,

Fabrice.

Samuel Thibault wrote:
> Hi,
> 
> The patch that qemu applies to bochs bios is a bit bugged:
> 
>  pci_pro_fail:
>    pop edi
>    pop esi
> -  sti
>    popf
>    stc
> +  and dword ptr[esp+4],0xfffffffc ;; reset CS.RPL for kqemu
>    retf
> 
> The and operation clears carry... So that pci functions always leave
> carry clear, and hence tell operating systems that they always work...
> This should rather be:
> 
>  pci_pro_fail:
>    pop edi
>    pop esi
> -  sti
>    popf
> +  and dword ptr[esp+4],0xfffffffc ;; reset CS.RPL for kqemu
>    stc
>    retf
> 
> Samuel
> 
> 
> _______________________________________________
> Qemu-devel mailing list
> Qemu-devel@nongnu.org
> http://lists.nongnu.org/mailman/listinfo/qemu-devel
> 
> 

      reply	other threads:[~2006-09-09 12:09 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-09-07  1:02 [Qemu-devel] PCI Bios fixup Samuel Thibault
2006-09-09 12:10 ` Fabrice Bellard [this message]

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