RE: [PATCHv2] virtio_console: Add support for remoteproc serial

[Sjur BRENDELAND]

> From: Michael S. Tsirkin [mailto:mst@xxxxxxxxxx]
> sjur.brandeland@xxxxxxxxxxxxxx wrote:
> > From: Sjur Brændeland <sjur.brandeland@xxxxxxxxxxxxxx>
> >
> > Add a simple serial connection driver called
> > VIRTIO_ID_RPROC_SERIAL (0xB) for communicating with a
> > remote processor in an asymmetric multi-processing
> > configuration.
> >
> > This implementation reuses the existing virtio_console
> > implementation, and adds support for DMA allocation
> > of data buffers and disables use of tty console and
> > the virtio control queue.
> 
> Can't repoteproc work with control queue?
> Reason I ask, there are known races when
> using config space and I was working on
> a spec change that uses control queue for
> all config accesses.

In my case rproc-serial will be used for transferring boot
image or crash-dump to a modem. In these scenarios the
execution environment is very limited (no OS) and  the size
and complexity of the virtio code at the modem should be kept
to a minimum.

The usage pattern in this case is also very simple,
the virtio device is opened only once, and only reopened
after a complete modem cold-start.

So the control queue is not appropriate for my use-case,
simplicity is the most important requirement.
(And currently the virtio config-space is not supported
by remoteproc anyway).

I don't know if other potential users of rproc_serial have more
complex use-cases in mind?

Regards,
Sjur



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