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Re: [Qemu-devel] [PATCH 1/5] char: Let the caller know how many bytes we
From: |
Jamie Lokier |
Subject: |
Re: [Qemu-devel] [PATCH 1/5] char: Let the caller know how many bytes were written in case of incomplete writes |
Date: |
Tue, 6 Apr 2010 14:30:02 +0100 |
User-agent: |
Mutt/1.5.13 (2006-08-11) |
Gerd Hoffmann wrote:
> On 04/06/10 13:05, Amit Shah wrote:
> >On (Tue) Apr 06 2010 [12:21:52], Gerd Hoffmann wrote:
> >>On 04/06/10 11:58, Amit Shah wrote:
> >>>>>It would certainly be beneficial for consumers of virtio-serial to be
> >>>>>notified of -EAGAIN so that the guest can be throttled till the chardev
> >>>>>catches up with the data being sent.
> >>>>
> >>>>EAGAIN should only ever occur if no bytes are written.
> >>>
> >>>Right. That, or just return 0 and let the caller handle the situation?
> >>
> >>Go with the usual unix semantics instead of creating something new.
> >>
> >>When something was written -- return the number of bytes. Caller has to
> >>compare with the length passed in to figure whenever it was a partial
> >>write or not.
> >>
> >>When nothing was written -- return the error.
> >
> >Unless Paul wants to never return recoverable error messages as he
> >mentioned in his first mail.
>
> Return value "0" usually means end-of-file, I would not use that for
> something else too. We have to agree on something though ...
Which is why EAGAIN was invented.
-- Jamie
- [Qemu-devel] [PATCH 4/5] virtio-console: Factor out common init between console and generic ports, (continued)
Re: [Qemu-devel] [PATCH 1/5] char: Let the caller know how many bytes were written in case of incomplete writes, Paul Brook, 2010/04/05
- Re: [Qemu-devel] [PATCH 1/5] char: Let the caller know how many bytes were written in case of incomplete writes, Amit Shah, 2010/04/05
- Re: [Qemu-devel] [PATCH 1/5] char: Let the caller know how many bytes were written in case of incomplete writes, Paul Brook, 2010/04/06
- Re: [Qemu-devel] [PATCH 1/5] char: Let the caller know how many bytes were written in case of incomplete writes, Amit Shah, 2010/04/06
- Re: [Qemu-devel] [PATCH 1/5] char: Let the caller know how many bytes were written in case of incomplete writes, Gerd Hoffmann, 2010/04/06
- Re: [Qemu-devel] [PATCH 1/5] char: Let the caller know how many bytes were written in case of incomplete writes, Amit Shah, 2010/04/06
- Re: [Qemu-devel] [PATCH 1/5] char: Let the caller know how many bytes were written in case of incomplete writes, Gerd Hoffmann, 2010/04/06
- Re: [Qemu-devel] [PATCH 1/5] char: Let the caller know how many bytes were written in case of incomplete writes,
Jamie Lokier <=
[Qemu-devel] Re: [PATCH 1/5] char: Let the caller know how many bytes were written in case of incomplete writes, Gerd Hoffmann, 2010/04/06
[Qemu-devel] Re: [PATCH 0/5] chardev, virtio-console: flow control, error handling, Gerd Hoffmann, 2010/04/06