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Date: Mon, 18 Oct 2010 12:09:23 +0200
From: Gerd Hoffmann <kraxel@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 1/2] pci: Automatically patch PCI device
	id in PCI ROM
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To: Anthony Liguori <anthony@codemonkey.ws>
Cc: Kevin Wolf <kwolf@redhat.com>, "Michael S. Tsirkin" <mst@redhat.com>, seabios@seabios.org, QEMU Developers <qemu-devel@nongnu.org>, Markus Armbruster <armbru@redhat.com>

On 10/15/10 23:05, Anthony Liguori wrote:
> On 10/15/2010 03:51 PM, Stefan Weil wrote:
>> PCI device with different device ids sometimes share
>> the same rom code. Only the device id and the checksum
>> differ in a boot rom for such devices.
>
> BTW, SeaBIOS doesn't reject ROMs when they're loaded via rombar, only
> when they're loaded via romfile.

SeaBIOS rejects them when loaded from the rom bar and doesn't reject 
them when loaded via fw_cfg.

Using the rom bar is the prefered way though, fw_cfg is only there for 
compatibility with older versions.

> Maybe it's better to use fw_cfg to explicitly tell SeaBIOS to ignore the
> PCI device id in the rom header for a certain device?

Patching the rom is fine IMHO.  Why create + use a separate 
communication path when we can use a much simpler approach?

cheers,
   Gerd