Re: [Qemu-devel] [PATCH 4/4] pci: use pci_config_header in pci.c

[Gerd Hoffmann <kraxel@redhat.com>]

Anthony Liguori wrote:
> Because the config structure is loaded after pci_register device and
> because the MMIO callbacks into the config space?  If you look at
> pci_default_read_config(), it actually does conversion from le to host
> CPU because that's what MMIO callbacks expect.

Yep.

> If you simply removed
> this, it would work.

Ah, *now* I see what you mean.

Well.  That assumes the guests always use the correct in{b,w,l}
instruction to access the config space values, i.e. never ever try to
use two inb reads for a 16bit value for example.  Or a inw for the lower
16 bits of a 32bit value because they know the high bits are zero anyway.

I have my doubts that this is a sane expectation.

> Of course, you'll have to audit each caller of
> pci_register_device() and make sure their config's get changed too.

Sure, that would be a *big* task & patch.

cheers,
  Gerd