[Qemu-devel] Re: [PATCH 0/8] (v2) chardev, virtio-console: flow control, error handling, fixes

[Paul Brook]

> Hello,
> 
> This patchset introduces flow control to virtio-console and
> chardev-based virtio serial ports. This series is based on the
> previous series I sent on Mar 31st (00/17: v4: virtio-serial fixes,
> new abi for port discovery)
> 
> The qemu chardevs can now return -EAGAIN when a non-blocking remote
> isn't ready to accept more data.
> 
> Comments?

This is a major change in semantics. Are you sure all users handle this 
correctly? My guess is that most of the devices don't.
EAGAIN isn't really a useful response unless you have some way of notifying 
the device that it can send more data.

Paul