Re: [Xen-devel] [XenSummit 2017] Shared coprocessor framework followup

[Andrii Anisov <andrii_anisov@xxxxxxxx>]

On 02.08.17 15:58, Edgar E. Iglesias wrote:
> Today it's an SMMUv2.
You would need to implement additional ops like [1].

> I don't necessarily think so. The context-switch would involve saving and
> restoring accelerator state aswell as re-programming the PL.
> With allocate/release, we only need to re-program the PL.
>
> Saving the state of the PL might be tricky since we don't know how to
> (we don't know the details of the acceelerator ahead of time).
> I guess we could somehow let the guest that owns the accellerator
> save/restore the state somehow but perhaps that brings us back
> in the direction of allocate/release semantics...
In this area context switch means to me a process to prepare a 
coprocessor to (start or continue) serving another domain tasks. It 
depends on a coprocessor nature and use-cases what the context switch 
physically means. And it is up to coprocessor platform driver how 
ctx_switch_from() and ctx_switch_to() are implemented [2]. Theoretically 
the framework should be platform agnostic.
BTW, the most up to date sources you can find here [3].

[1] 
https://github.com/xen-troops/xen/commit/a01f7ccf8bd5e9069f82c6ea6b92e2faca4920d9
[2] 
https://github.com/xen-troops/xen/blob/vgpu-dev/xen/arch/arm/coproc/coproc.h#L81
[3] https://github.com/xen-troops/xen/tree/vgpu-dev

--

*Andrii Anisov*



_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel