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Re: [Qemu-devel] [PATCH] pci: implement bridge filtering

From: Avi Kivity
Subject: Re: [Qemu-devel] [PATCH] pci: implement bridge filtering
Date: Tue, 20 Sep 2011 14:44:26 +0300
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:6.0.2) Gecko/20110906 Thunderbird/6.0.2

On 09/20/2011 11:09 AM, Wen Congyang wrote:
At 09/14/2011 09:48 AM, Wen Congyang Write:
>  At 09/05/2011 02:13 AM, Michael S. Tsirkin Write:
>>  Support bridge filtering on top of the memory
>>  API as suggested by Avi Kivity:
>>  Create a memory region for the bridge's address space.  This region is
>>  not directly added to system_memory or its descendants.  Devices under
>>  the bridge see this region as its pci_address_space().  The region is
>>  as large as the entire address space - it does not take into account
>>  any windows.
>>  For each of the three windows (pref, non-pref, vga), create an alias
>>  with the appropriate start and size.  Map the alias into the bridge's
>>  parent's pci_address_space(), as subregions.
>>  Signed-off-by: Michael S. Tsirkin<address@hidden>
>>  ---
>>  The below seems to work fine for me so I applied this.
>>  Still need to test bridge filtering, any help with this
>>  appreciated.
>  I test bridge filtering, and the BAR still can be visible on guest even if
>  I change the memory region.

Hi Michael S. Tsirkin:
I test pci bridge filtering on real hardware, and I find that I can mmap
the resource after I change the memory base and memory limit(The BAR should
be not visible on OS after changing the memory region).

So I try to write and read to the BAR. Here is my test result:
1. Before changing the pci bridge's memory region, I can read and write to the 
memory, and
    I can get the same value that I write.

2. After changing the pci bridge's memory region, I can still read and write to 
the memory,
    but it is very slow, and I can not get the same value that I write(The 
value is always 0).

Does this result means that pci bridge filtering works fine?

Yes.  Instead of hitting the BAR, you hit the default mmio handler.

error compiling committee.c: too many arguments to function

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