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From: Paolo Bonzini <pbonzini@redhat.com>
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Date: Wed, 15 Jun 2016 00:05:18 +0200
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Subject: Re: [Qemu-devel] [PATCH v4 04/11] nbd: Improve server handling of
 bogus commands
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To: Alex Bligh <alex@alex.org.uk>
Cc: Eric Blake <eblake@redhat.com>, "qemu-devel@nongnu.org" <qemu-devel@nongnu.org>, qemu block <qemu-block@nongnu.org>, "nbd-general@lists.sourceforge.net" <nbd-general@lists.sourceforge.net>



On 14/06/2016 17:59, Alex Bligh wrote:
> 
>> On 14 Jun 2016, at 16:11, Paolo Bonzini <pbonzini@redhat.com> wrote:
>>
>>> To illustrate the problem, look consider what qemu itself would do as
>>> a server if it can't buffer the entire read issued to it.
>>
>> Return ENOMEM?
> 
> Well OK, qemu then 'works' on the basis it breaks another
> part of the spec, which is coping with long reads.

ENOMEM is a documented error code, and the limits extension will help
with that as well.

>> However, it looks like the
>> de facto status prior to structured replies is that the error is in the
>> spec, and this patch introduces a regression.
> 
> Well, I guess the patch makes it work the same as the
> reference server implementation and the spec, which I'd
> consider a fix. My view is that the error is in the
> kernel client.

... and QEMU and BSD.  What good is a server that doesn't interoperate
(albeit only in error cases) with any client?

Paolo