Re: [Qemu-devel] PCI: Memory mapped / ROM resources

[Gianni Tedesco <gianni@scaramanga.co.uk>]

On Wed, 2004-05-26 at 22:45, Hetz Ben Hamo wrote:
> Let me see if I get this straight:
> 
> With your patches, will I be able to use a real PCI card within the emulator? 
> for example: Would I be able to use a PCI graphics card which is not being 
> used by XFree under Linux?

Yes basically. However there are some technical limitations which mean
that for most PCI devices this will be unusable as it is impossible
(well, very difficult) to emulate PCI DMA.

Also, I don't think VGA cards will work correctly under this scheme
without hacking qemu's BIOS code.

> Also, if you plan to use real PCI cards under guest OS, you might need to 
> create some "locking" mechanism so that the host OS cannot use them, nor 
> another instance of QEMU which will run in parallel (and I see already few 
> people running few QEMU instances at once ;)

Yeah, I think we can tell if the kernel is using the device already buy
checking if a driver is associated with it. Excluding multiple copies of
qemu can probably be done with an advisory file lock. I'll look in to
this. I was basically ignoring these issues up till now as it is quite a
'hacker tool' for the moment :)

-- 
// Gianni Tedesco (gianni at scaramanga dot co dot uk)
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