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Date: Fri, 9 Sep 2011 10:34:39 +0300
From: "Michael S. Tsirkin" <mst@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] pci: add standard bridge device
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To: Wen Congyang <wency@cn.fujitsu.com>
Cc: Kevin Wolf <kwolf@redhat.com>, Isaku Yamahata <yamahata@valinux.co.jp>, Avi Kivity <avi@redhat.com>, qemu-devel@nongnu.org

On Fri, Sep 09, 2011 at 03:24:54PM +0800, Wen Congyang wrote:
> At 09/09/2011 03:12 PM, Michael S. Tsirkin Write:
> > On Fri, Sep 09, 2011 at 02:43:24PM +0800, Wen Congyang wrote:
> >>> However, filtering doesn't work.  You could put a BAR outside the
> >>> filtered area and it would be visible to the guest.
> >>>
> >>
> >> I test it on real hardware. If I put a BAR outside the filterer area, and
> >> then run 'lspci -vv', the BAR does not change:
> > 
> > ...
> > 
> > 
> >> The BAR1 is feafbc00, and it is in the bus2's range.
> >> I map the BAR(mmap /sys/bus/pci/devices/0000\:03\:01.0/resource1), and find
> >> I can read and write the memory.
> >>
> >> Thanks
> >> Wen Congyang
> > 
> > So, it's as expected. Nothing seems wrong with this picture. But
> > this is not the test that Avi suggested.
> 
> Sorry for my misunderstand.
> My question is: How to put a BAR outside the filterer area,

Write into address/limit registers on the bridge to make them
not cover the BAR behind.

> and how to know
> whether it is visible?
> 
> Thanks
> Wen Congyang

Read the BAR memory as you did.

-- 
MST