Re: [PATCH v3] used ring: specify legacy behaviour for len field

[Rusty Russell <rusty@rustcorp.com.au>]

Paolo Bonzini <pbonzini@redhat.com> writes:
> On 20/04/2015 16:24, Michael S. Tsirkin wrote:
>> many hypervisors implemented len field incorrectly.
>> Document existing bugs in the legacy sections.
>> 
>> VIRTIO-141
>> 
>> Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
>> Cc: Paolo Bonzini <pbonzini@redhat.com>
>> Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
>> ---
>> 
>> As Paolo pointed out, most devices don't really need the used len
>> field. Going over QEMU code, I found more devices that seem buggy.
>> So let's just document that drivers should ignore len in
>> legacy mode, for all devices where this makes sense (i.e.  except
>> receive queue for serial and net devices, and the rng).
>
> Looks good.  Indeed in this cases len is used.

Indeed.

Thanks,
Rusty.