From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Vrabel <david.vrabel@citrix.com>
Subject: Re: [PATCH 2/3] public/io/netif.h: document control
 ring and toeplitz hashing
Date: Mon, 4 Jan 2016 11:18:06 +0000
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To: Paul Durrant <Paul.Durrant@citrix.com>, "xen-devel@lists.xenproject.org" <xen-devel@lists.xenproject.org>
Cc: "Keir (Xen.org)" <keir@xen.org>, "Tim (Xen.org)" <tim@xen.org>, Ian Campbell <Ian.Campbell@citrix.com>, Jan Beulich <jbeulich@suse.com>, Ian Jackson <Ian.Jackson@citrix.com>
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On 04/01/16 11:14, Paul Durrant wrote:
>>>> You should use the standard ring format and infrastructure.
>>>
>>> Is there one for variable message size rings? I didn't find one. I
>>> don't want to use the fixed size balanced ring macros for control
>>> messages as fixed size messages really aren't appropriate in this case.
>>
>> Perhaps union the request/response message types with a uint8_t
>> pad[1024] and use this as the request/response type?
>>
> 
> The problem is that this places a 1k limit on the message size,
> which
> is not there in the scheme I'm proposing. I'd rather not bake that limit
> in if I don't have to.

>>>>> + * |                      req[1024]                |
                                 ^^^^^^^^^
Surely this limits your size to 1024 bytes?

Also if you need bigger messages you can grant those areas separately
and pass a grant ref through the ring, or you can chunk the message to
fit in several requests/responses.

David