From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Chen, Tiejun" <tiejun.chen@intel.com>
Subject: Re: [v5][PATCH 2/5] xen,
 gfx passthrough: create pseudo intel isa bridge
Date: Wed, 25 Jun 2014 17:28:48 +0800
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To: "Michael S. Tsirkin" <mst@redhat.com>
Cc: peter.maydell@linaro.org, xen-devel@lists.xensource.com, stefano.stabellini@eu.citrix.com, allen.m.kay@intel.com, qemu-devel@nongnu.org, Kelly.Zytaruk@amd.com, yang.z.zhang@intel.com, anthony@codemonkey.ws, anthony.perard@citrix.com, pbonzini@redhat.com
List-Id: xen-devel@lists.xenproject.org

On 2014/6/25 17:21, Michael S. Tsirkin wrote:
> On Wed, Jun 25, 2014 at 05:14:30PM +0800, Chen, Tiejun wrote:
>> On 2014/6/25 17:04, Michael S. Tsirkin wrote:
>>> On Wed, Jun 25, 2014 at 04:48:02PM +0800, Chen, Tiejun wrote:
>>>> On 2014/6/25 16:43, Michael S. Tsirkin wrote:
>>>>> On Wed, Jun 25, 2014 at 04:39:07PM +0800, Chen, Tiejun wrote:
>>>>>>> In fact it's exactly what passthrough does.
>>>>>>> I wonder if more bits from ./hw/i386/kvm/pci-assign.c
>>>>>>> can be reused. How do you poke at the host device? sysfs?
>>>>>>
>>>>>> Yes, sysfs.
>>>>>>
>>>>>> Thanks
>>>>>> Tiejun
>>>>>
>>>>> Then you should be able to re-use large chunks of
>>>>> ./hw/i386/kvm/pci-assign.c: basically everything
>>>>> that deals with emulation.
>>>>
>>>> Do you mean those hooks to get info from the real device? Xen have its own
>>>> wrapper, xen_host_pci_get_block(), so we always go there in xen scenario.
>>>>
>>>> Thanks
>>>> Tiejun
>>>
>>> Yes and that's not good.  We have two pieces of code doing mostly
>>> identical things slightly differently.
>>> hw/i386/kvm/pci-assign.c is a bit younger so it's cleaner,
>>> but these really need to be unified.
>>>
>>
>> Sorry, take a look at this again,
>>
>> xen_host_pci_get_block(XenHostPCIDevice *d, int pos, uint8_t *buf, int len)
>> 	|
>> 	+ xen_host_pci_config_read(d, pos, buf, len)
>> 		|
>> 		+ pread(d->config_fd, buf, len, pos)
>>
>> I thinks this should be same as kvm.
>>
>> Thanks
>> Tiejun
>
> get_block is trivial.
>
> I really mean the whole PT infrastructure for
> - discovering host devices through sysfs
> - virtualizing devices
>
> rom, bars, msi ...
> the list goes on.
>
> logic is mostly the same.
>

Looks you mean we can unify the entire PT infrastructure between kvm and 
xen inside qemu. But I'm afraid its not easy to do in a short time, so 
maybe we can queue this as next phase.

Thanks
Tiejun