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Re: [Qemu-devel] [PATCH 2/3] Add a new PCI region type to supports 64 bi

From: Alexey Korolev
Subject: Re: [Qemu-devel] [PATCH 2/3] Add a new PCI region type to supports 64 bit ranges
Date: Thu, 29 Dec 2011 16:57:53 +1300
User-agent: Mozilla/5.0 (X11; Linux i686; rv:8.0) Gecko/20111124 Thunderbird/8.0

On 29/12/11 00:30, Michael S. Tsirkin wrote:
On Wed, Dec 28, 2011 at 06:26:05PM +1300, Alexey Korolev wrote:
This patch adds PCI_REGION_TYPE_PREFMEM_64 region type and modifies types of
variables to make it possible to work with 64 bit addresses.

Why I've added just one region type PCI_REGION_TYPE_PREFMEM_64 and haven't
added PCI_REGION_TYPE_MEM_64? According to PCI architecture
specification, the
bridges can describe 64bit ranges for prefetchable type of memory
only. So it's very
unlikely that devices exporting 64bit non-prefetchable BARs.
Might happen for system devices I guess.

this code will work
with 64bit non-prefetchable BARs unless the PCI device is not behind
the secondary bus.
So what happens if such a device is on root bus?
If a device is on the root bus and have BAR flags 0x4 (TYPE_MEMORY and 64 bit), memory will be allocated in 64bit range all flags remain the same. I did this just out
of curiosity and this appears to work well.

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