[libvirt] error: server response too large

[Claudio Bley]

At Mon, 7 Oct 2013 11:31:48 +0100,
Daniel P. Berrange wrote:
> 
> > I've also tested your patch, and it seems 256 KB of data is still a
> > bit too large:
> > 
> > virsh # screenshot 2 /tmp/test
> > error: could not receive data from domain 2
> > error: packet 262168 bytes received from server too large, want 262144
> > 
> > The max payload size is computed as:
> > 
> > VIR_NET_MESSAGE_MAX = 16777216
> > VIR_NET_MESSAGE_HEADER_MAX = 24
> > VIR_NET_MESSAGE_PAYLOAD_MAX = (VIR_NET_MESSAGE_MAX - VIR_NET_MESSAGE_HEADER_MAX) = 16777192
> > 
> > So, it seems the legacy max payload size is actually 262120; I tested
> > it and it works.
> > 
> > ------------------- 8< ------ >8 ---------------------------
> > Subject: [PATCH] Adjust legacy max payload size to account for header
> >  information
> > Organization: AV-Test GmbH, Germany
> > 
> > Commit 27e81517a87 set the payload size to 256 KB, which is
> > actually the max packet size, including the size of the header.
> > 
> > Reduce this by VIR_NET_MESSAGE_HEADER_MAX (24) and set
> > VIR_NET_MESSAGE_LEGACY_PAYLOAD_MAX to 262120.
> > 
> > Signed-off-by: Claudio Bley <cbley at av-test.de>
> > ---
> >  src/rpc/virnetprotocol.x |    2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/src/rpc/virnetprotocol.x b/src/rpc/virnetprotocol.x
> > index 1eae7cb..7b6f753 100644
> > --- a/src/rpc/virnetprotocol.x
> > +++ b/src/rpc/virnetprotocol.x
> > @@ -55,7 +55,7 @@ const VIR_NET_MESSAGE_INITIAL = 65536;
> >   * payload size. We need to remember this for compat with
> >   * old clients.
> >   */
> > -const VIR_NET_MESSAGE_LEGACY_PAYLOAD_MAX = 262144;
> > +const VIR_NET_MESSAGE_LEGACY_PAYLOAD_MAX = 262120;
> > 
> >  /* Maximum total message size (serialised). */
> >  const VIR_NET_MESSAGE_MAX = 16777216;
> 
> Damn, yes, you are correct. The original value was 262120, I
> copied the wrong value.
> 
> THe commit which changed it first was
> 
>   commit eb635de1fed3257c5c62b552d1ec981c9545c1d7
>   Author: Michal Privoznik <mprivozn at redhat.com>
>   Date:   Fri Apr 27 14:49:48 2012 +0200
> 
>     rpc: Size up RPC limits
> 
>    /* Size of message payload */
>   -const VIR_NET_MESSAGE_PAYLOAD_MAX = 262120;
>   +const VIR_NET_MESSAGE_PAYLOAD_MAX = 4194280;

I amended my commit message referring to Michal's commit
and pushed.

Are you pushing to the maintenance branches, then?

Claudio
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