Re: [Xen-devel] Source of guest-physical address in PCI BAR for HVM domain?

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

hvmloader should expand the mmio hole if it detects that there is not enough
space to map all PCI resources.

 -- Keir

On 7/1/08 21:39, "David Stone" <unclestoner@xxxxxxxxx> wrote:

> Thanks for the pointer...I believe I see the problem.  The code in
> pci_setup starts granting guest-physical address space to PCI devices
> at 0xF0000000.  The problem in my case is, my PCI-XP graphics card
> wants 256MB of guest-phyical address space for its video RAM.  That
> wraps around to 0x00000000.  It doesn't look like the code handles
> this, so it just merrily wraps around and ends up assigning memory
> ranges that are already in use for system RAM!
> 
> I'll have a look at improving this...
> 
> Dave
> 
> On Jan 6, 2008 6:15 PM, Keir Fraser <Keir.Fraser@xxxxxxxxxxxx> wrote:
>> I see there's been a small email thread on this topic now, but I want to
>> point out that the code that configures the PCI BARs initially is not in the
>> rombios code but is in the hvmloader code. See
>> tools/formware/hvmloader/hvmloader.c:pci_setup().
>> 
>>  -- Keir
>> 
>> 
>> On 4/1/08 16:35, "David Stone" <unclestoner@xxxxxxxxx> wrote:
>> 
>>> I understand that eventually it would be the HVM guest OS that would
>>> write to the PCI configuration IO port which would get caught be Xen
>>> and passed along to qemu.  But, this is happending early in the boot
>>> process before the guest OS proper is even running.  My understanding
>>> of how PCI systems work is that the BIOS first configures (a subset
>>> of) the PCI devices, and then the once the real OS is initializing it
>>> can re-configure any PCI devices it wants to.  Can someone tell me if
>>> this is correct?
>>> 
>>> If so, shouldn't the early PCI configuration from the BIOS be coming
>>> from qemu itself?  My understanding is that qemu emulates a BIOS for
>>> HVM domains.
>> 
>> 
>> 



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