Re: [Qemu-devel] Re: [PATCH 1/2] pci: Automatically patch PCI vendor id and device id in PCI ROM

[Stefan Weil <weil@mail.berlios.de>]

Am 18.10.2010 21:03, schrieb Michael S. Tsirkin:
> On Mon, Oct 18, 2010 at 01:42:06PM -0500, Anthony Liguori wrote:
>>>> +/* Patch the PCI vendor and device ids in a PCI rom image if 
>>>> necessary.
>>>> + This is needed for an option rom which is used for more than one 
>>>> device. */
>>>> +static void pci_patch_ids(PCIDevice *pdev, uint8_t *ptr, int size)
>>> let's return an error code on malformed roms so management can 
>>> detect errors?
>>
>> A bad/missing PnP header does not mean it's an invalid ROM.
>
> I don't see this as a generic capability - rather a specific
> hack that helps reduce some duplication for eepro100 and friends.
> As such, if we can't patch the id we know it's an invalid file.

There is already some kind of error feedback: the rom will not work.
For etherboot roms, booting from network won't work.

This is a qemu internal error, so more error handling is not needed.

Users who configure a device with their own rom file don't
need an id patch, and their rom data will not be patched
because they normally specify a rom file with correct ids.
For the rare case where they configure a rom with a "wrong"
id, their rom data will be patched (something they don't expect)
or not modified because of the sanity checks (then the rom
is ignored by the bios).

Maybe a more perfect solution would only patch the preconfigured
rom files but not user configured files, but I don't think we
need this degree of perfection.

Regards,
Stefan