Re: questions of vm save/restore on arm64

[Julien Grall <julien.grall@arm.com>]

Hello,

First thing, the time in the mail headers seems to be wrong. Maybe 
because of a wrong timezone?

I got: 04/06/16 02:32 however we are still the 3rd in my timezone.

On 04/06/16 02:32, Chenxiao Zhao wrote:
>
>
> On 6/3/2016 3:16 AM, Julien Grall wrote:
>> Hello,
>>
>> On 03/06/16 18:05, Chenxiao Zhao wrote:
>>> I finally found out that the problem is that the toolstack did not get
>>> corret p2m_size while sending all pages on save(always be zero). After I
>>> fixed that, the guest could be restored but guest kernel caught
>>> handle_mm_fault().
>>>
>>> where do you think I'm going to investigate, guest kernel hibernation
>>> restore or xen?
>>
>> The hibernation support for ARM64 has only been merged recently in the
>> kernel. Which kernel are you using?
>
> Hi Julien,
>
> I'm using a linaro ported Linux kernel 4.1 for hikey from this link.
>
> https://github.com/96boards/linux/tree/android-hikey-linaro-4.1
>
> I also applied following patches to make the kernel support hibernation.

This looks the wrong way to do it as this series may requires some 
patches which have been upstreamed before hand.

Linux upstream seems support to the hikey board [1]. Any reason to not 
using it?

> [1] http://www.spinics.net/lists/arm-kernel/msg477769.html
> [2] http://lists.xen.org/archives/html/xen-devel/2015-12/msg01068.html
>
>>
>> Also, what are the modifications you have made to support Xen
>> suspend/resume for ARM64?
>
> I believe I have posted my modifications on xen in the first mail of
> this thread.

I mean in Linux. The patch from Ian Campbell does not have any kind of 
support for ARM64.

For instance arch/arm/xen/suspend.c needs to be built for ARM64. So I am 
wondering if your kernel has support of hibernation...

>
>  From my understanding, a kernel hibernation will cause kernel to save
> memories to disk(swap partition). But on guest save progress, the
> hibernation for domU does not make the guest save memories to disk. it's
> more like suspend all processes in guest, and memors actually depends on
> xen toolstack to save the pages to file. Am I correct?

You are using an older tree with a patch series based on a newer tree.

So I would recommend you to move to a newer tree. If it is not possible, 
please test that hibernation works on baremetal.

Regards,

[1] https://lists.96boards.org/pipermail/dev/2016-May/000933.html

-- 
Julien Grall

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