[PATCH v2 00/11] Drivers for gunyah hypervisor

[Dmitry Baryshkov]

On 09/08/2022 02:38, Elliot Berman wrote:
> 
> 
> On 8/2/2022 2:24 AM, Dmitry Baryshkov wrote:
>> I might be completely wrong about this, but if my in-mind picture of 
>> Gunyah is correct, I'd have implemented the gunyah core subsytem as 
>> mailbox provider, RM as a separate platform driver consuming these 
>> mailboxes and in turn being a remoteproc driver, and consoles as 
>> remoteproc subdevices. >
> 
> The mailbox framework can only fit with message queues and not doorbells 
> or vCPUs. The mailbox framework also relies on the mailbox being defined 
> in the devicetree. RM is an exceptional case in that it is described in 
> the devicetree. Message queues for other VMs would be dynamically 
> created at runtime as/when that VM is created. Thus, the client of the 
> message queue would need to "own" both the controller and client ends of 
> the mailbox.

I'd still suggest using the mailbox API for the doorbells. You do not 
have to implement the txdone, if I'm not mistaken.

> 
> RM is not loaded or managed by Linux, so I don't think remoteproc 
> framework provides us any code re-use except for the subdevices code. 
> Remoteproc is much larger framework than just the subdevices code, so I 
> don't think it fits well overall.
> 
>> I can assume that at some point you would like to use Gunyah to boot 
>> secondary VMs from the primary VM by calling into RM, etc.
>> Most probably at this moment a VM would be allocated other bells, 
>> message queues, etc. If this assumption is correct, them the VM can 
>> become a separate device (remoteproc?) in the Linux device tree.
>>
>> I might be wrong in any of the assumptions above. Please feel free to 
>> correct me. We can then think about a better API for your usecase.
>>
> 
> We don't want to limit VM configuration to the devicetree as this limits 
> the number and kinds of VMs that can be launched to build time. I'm not 
> sure if you might have seen an early presentation of Gunyah at Linaro? 
> In the early days of Gunyah, we had static configuration of VMs and many 
> properties of the VMs were described in the devicetree. We are moving 
> away from static configuration of VMs as much as possible.

ack, this is correct.

> 
> [1]: https://chromium.googlesource.com/chromiumos/platform/crosvm
> 

-- 
With best wishes
Dmitry