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

[Yuji Shimada <shimada-yxb@xxxxxxxxxxxxxxx>]

On Wed, 23 Jul 2008 11:16:31 +0800
"Cui, Dexuan" <dexuan.cui@xxxxxxxxx> wrote:
> 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.
> 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.

Hi Cui,

What do you think about the following idea?
  - For 3.3, modify xend to have limited saving/restoring and resetting
    functions.
  - For 3.4, modify pciback to have proper saving/restoring and
    resetting functions.

The purpose of saving is to save the values configured by firmware. So
the best timing of saving the value is when dom0 starts. But if saving
the values when dom0 starts, pciback is the best place to save/restore.
If pciback saves/restores the values, we need many codings. So it is
difficult to achieve it in 3.3.

So for 3.3, there is a way that saving the value just before resetting.
It is possible xend saves/restores the value, I think. In this case,
xend don't need saving the values in xenstore. Because interval between
saving and restoring is small.

My idea is summarized as follows:

Xen    Timing              Where      Difficulty
3.3    before resetting    xend       easy
3.4    when Dom0 starts    pciback    hard

Thanks.

--
Yuji Shimada


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