RE: [Xen-devel] [PATCH] Improve the current FLR logic

["Cui, Dexuan" <dexuan.cui@xxxxxxxxx>]

Yuji Shimada wrote:
> On Fri, 18 Jul 2008 18:43:49 +0800
> "Cui, Dexuan" <dexuan.cui@xxxxxxxxx> wrote:
>> Hi Yuji,
>> Thanks for your advice!
>> To restore the values of the PCIe registers to the original values
>> the firmware (and Dom0?) configues, we need to store the original
>> values somewhere. Maybe we can restore the info into xenstore?
> 
> Hi Cui,
> Xenstore is OK, but pciback is better place, I think.
> Because device driver should configure devices.
I think xenstore seems to be a little ugly place to remember the proper
values of all or part of registers of all the devices in the system.
I agree pciback is a good place.

> If we do it in pciback, the coding might be difficult. But the
> whole architecture will be simple.
Yes. Now I realize pciback seems to be the best place to do most of the
FLR logic.
But this needs modify pciback and add interfaces for Control Panel.
I'm not sure the changes can be small enought to be in 3.3.

> 
> I think the following saving/restoring timing is good.
>   - saving    : after pciback bind device
>   - restoring : after xend writes SBDF into xenstore
>                 before pciback removes backend device
> 
>>> What do you think about following method?
>>> 
>>>      1. create the table, and fill offset, size, etc. of registers
>>>         to save/restore into the table.
>>> 
>>>      2. save/restore registers based on the table.
>> This sounds nice.
>> Where should we store the table?
> 
> I don't think device specific tables are required.
> So we only have to create one table.
> xend (or pciback if you implement saving/restoring in pciback) is good
> place, I think.
> 

Thanks,
-- Dexuan

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