Re: [Qemu-devel] chardev's and fd's in monitors

[Markus Armbruster <armbru@redhat.com>]

"Dr. David Alan Gilbert" <dgilbert@redhat.com> writes:

> * Markus Armbruster (armbru@redhat.com) wrote:
>> "Daniel P. Berrange" <berrange@redhat.com> writes:
[...]
>> > Realistically all the major backend subsystems (chardev, network, block,
>> > ui and migration) need to be converted to Error ** propagation, since
>> > they all ultimately call into some common code that reports Error **.
>> 
>> Infrastucture generally doesn't know how it's used, which means
>> error_report() is generally wrong there.  Sufficiently simple functions
>> can keep returning -errno, null, whatever, but the interesting stuff
>> needs to use Error.
>> > Very few places will end up being able to stick with -errno, or plain
>> > error_report in the long term.
>> 
>> Not sure about "very few".  Less than now.  We'll see.
>
> I'd also prefer we got the very-few level; Migration used to be
> characterised by getting a 'load of migration failed -22' and having
> no clue in the logs to why; I've slowly fought back to be able
> to get an error from the lowest level that caused the failure.
> I want more of that, so that when someone gets a rare failure in the field
> I can see why.

When it's about details that are only useful for debugging, logging
might be a practical alternative.  No excuse for shoddy error reporting,
of course.