Re: [PATCH RFC v1 00/14] xen: arm: support for save restore and dead migration

[Andrew Cooper <andrew.cooper3@citrix.com>]

On 09/12/15 14:31, Ian Campbell wrote:
> For arm32 + gicv2 systems the following supports apparently successful
> save/restore as well dead migrate a domain.
>
> There are several caveats/blockers, hence RFC.
>
>  * GIC v2 support only, no GIC v3 at all
>  * ARM32 only. Doesn't even build for ARM64 (vfp state handling needs
>    adjustment)
>  * No live migration, only "dead" (no logdirty support yet)
>  * Have not fully audited the set of state which needs to be saved (i.e. I
>    might have missed some registers or something)
>
> On the flip side, thanks to migration v2 the toolstack side of this
> practically trivial.

Glad to hear this.

> This is (of course) using the current Xen hvm blob handling strata, which I
> believe there are plans afoot to rework along the lines of the libxc/libxl
> migration v2 protocol.

Yes - I have plans as part of fixing cpuid handling for x86.

>
> For now I have no problem waiting and reworking in that vein as things
> progress, clearly the blockers/caveats (logdirty support in particular) are
> going to take some time to sort out.
> This is all based (very distantly) on some original patches from Evgeny
> Fedotov and Junghyun Yoo (both of Samsung) however very little of that code
> remains here.
>
> As well as the Xen series there will be a single Linux patch too, I'll only
> CC ARM folks on that one.

Something towards the end of this series should update
docs/features/migration.pandoc to indicate the presence of ARM support.

~Andrew