Re: [PATCH v10 03/10] admin: introduce group administration commands

["Michael S. Tsirkin" <mst@redhat.com>]

On Thu, Mar 02, 2023 at 03:19:12PM -0500, Stefan Hajnoczi wrote:
> On Thu, Mar 02, 2023 at 06:40:29PM +0000, Parav Pandit wrote:
> > 
> > > From: Michael S. Tsirkin <mst@redhat.com>
> > > Sent: Thursday, March 2, 2023 8:05 AM
> > 
> > > +When \field{status} is VIRTIO_ADMIN_STATUS_OK, \field{status_qialifier}
> > > +is reserved and set to zero by the device.
> > > +
> > s/status_qialifier/status_qualifier
> > Missed from v10 of Feb.
> > 
> > > +When \field{status} is VIRTIO_ADMIN_STATUS_EINVAL, the following table
> > > +describes possible \field{status_qialifier} values:
> > s/status_qialifier/status_qualifier
> > 
> > Can you please add other useful error codes in addition to the EINVAL?
> > Few that we are needed EAGAIN, ENOMEM, EBUSY, ENODEV.
> 
> Please define a unique constant for each error condition that can occur
> instead of sharing catch-all errno constants between multiple error
> conditions. If a driver wants to squash them together into an errno,
> that's fine, but I think doing this at the hardware interface level is
> just propagating the mistakes of errnos.
> 
> Only status_qualifier is needed and the vague status field can be
> dropped. It's not clear to me why adding EAGAIN, ENOMEM, EBUSY, and
> ENODEV is useful. They have no meaning to the driver, only the
> status_qualifier really indicates what is going on.

At a high level at the moment we have only two cases:
- ok
- invalid input supplied by driver

maybe we will have more reasons for a failure - remains to
be seen.





> 
> I'm sure you guys have discussed this previously, but please provide
> rationale in the spec because it looks weird to someone with fresh eyes.
> 
> Stefan

Really most drivers just want to propagate errno to userspace.
All the detailed reporting is for sure well intentional but
in the end it is at best printed into log - end to end
people just end up with a switch statement
converting these to errno codes.
So we are passing them from device and this way there will be
some uniformity.


-- 
MST