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Re: [Xen-devel] [ARM] Native application design and discussion (I hope)

On 24.04.17 21:08, Stefano Stabellini wrote:

If we are speaking about shared coprocessors framework, we need here several
  - MMIO access emulation
This could be run as EL0 app.
But even now, the MMIO access emulation has something to do with the real hardware under the circumstances.

  - periodic actions (scheduling) which at least will include IOMMU
reconfiguration and some actions with coprocessor hardware itself in runtime
  - coprocessor interrupts handling and redistribution to target domains
These would be better as stubdoms. Or, if they are simple enough, in
the hypervisor directly.

Assuming that MMIO access emulation is done in an EL0 app, how many
types of calls does it need to make to these two components?
With current implementation - none, but I guess it should be able to trigger scheduling actions. Also access emulation does collect some data what is used by context switching process.

As far as I can tell, without looking at the existing code, the options
1) everything in a stubdom
2) MMIO access emulation as EL0 app, the rest in a stubdom
3) MMIO access emulation as EL0 app, the rest in Xen

The right approach depends on the type of interactions between MMIO
access emulation and the rest of the shared coprocessors framework. Does
this make sense?
Thank you for your ideas and comments.
We will see what would be the EL0 app and how would evolve our vision of SCF along further implementation.
Currently we have pretty much unclarity here to get the decision postponed.


*Andrii Anisov*

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