Re: [Qemu-devel] [PATCH 1/5] char: Let the caller know how many bytes were written in case of incomplete writes

[Amit Shah]

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.

                Amit