RE: [Xen-devel] [PATCH] Dom0 Kernel - Fixes forsaving/restoringMSI/MSI-X across Dom0 S3

["Jan Beulich" <jbeulich@xxxxxxxxxx>]

>>> "Shan, Haitao" <haitao.shan@xxxxxxxxx> 24.11.08 14:55 >>>
>Yes, clear enough as Kevin said. That is what I saw why S3 failed when AHCI is 
>enabled (AHCI uses MSI). I do not know whether it
>is also the reason that Jan sees the need to add force unbind support of MSI.
>I have another question for saving/restoring in Xen if we do not use a new 
>hypercall. Devices are controller by dom0. At the point
>Xen wants to save MSI during S3, dom0 may already places that device in D3hot 
>state, or it may also cease the device's function
>via pci_disable_device. I doubt whether Xen can read device MMIO at that time.

But - as asked before - shouldn't the device undergo full re-initialization 
after coming out of D3? Iirc, the AHCI/S3 bug results in a 
cannot-rebind-because-already-bound error, which would indicate to me that the 
driver tries to create a new binding, and hence doesn't really need the 
device's state saved (admitted, I didn't look closely at the driver's code so 
far). It instead may just need Xen to clean up its internal state properly. But 
really, I'm in no way a suspend/resume expert...

Jan


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