Re: [Qemu-devel] [PATCH 0/2] pci: 64bit bits

[Avi Kivity <avi@redhat.com>]

On 05/02/2012 06:54 PM, Gerd Hoffmann wrote:
> On 05/02/12 17:33, Avi Kivity wrote:
> > On 05/02/2012 05:02 PM, Gerd Hoffmann wrote:
> >>   Hi,
> >>
> >> seabios (master branch) just got 64bit pci support.  When running out of
> >> address space in the pci memory window below 4G (0xe0000000+) seabios
> >> will map 64bit pci bars above 4G to make room below 4G.
> >>
> >> This patch series carries two little patches for qemu to adapt it to the
> >> seabios changes.  First patch creates a memory window for the 64bit pci
> >> bars.  Second patch adds a 64bit option to the ivshmem driver, which
> >> allows to use huge shared memory chunks.
> > 
> > What happens if a pre-64-bit-pci guest boots on such a setup?
>
> If it worked before it should continue to work just fine.  Note that the
> 64bit bars are only mapped above 4G in case there is not enough address
> space below 4G, so existing setups should never ever see bars mapped high.

I see.  I guess it depends on the algorithm for selecting the BAR to be
evicted, but if everything fitted before, it should fit now as well.  If
it didn't, then a different device may break in each of the two cases.

-- 
error compiling committee.c: too many arguments to function