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Date: Wed, 02 May 2012 17:54:50 +0200
From: Gerd Hoffmann <kraxel@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH 0/2] pci: 64bit bits
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To: Avi Kivity <avi@redhat.com>
Cc: qemu-devel@nongnu.org

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.

cheers,
  Gerd