On Tue, Nov 01, 2011 at 01:27:56PM -0500, Anthony Liguori wrote: > On 10/20/2011 10:13 AM, Daniel P. Berrange wrote: > >On Fri, Oct 07, 2011 at 04:49:13PM +0530, Aneesh Kumar K.V wrote: > >>On Fri, 7 Oct 2011 10:27:56 +0100, "Daniel P. > >>Berrange"<berra...@redhat.com> wrote: > >>>On Thu, Sep 29, 2011 at 04:22:16PM +0100, Daniel P. Berrange wrote: > >>>I've done some tests with ever larger mount tags, and managed to increase > >>>the MAX_TAG_LEN value to 1023 before I started getting guest failures. > >>> > >>>So if the config space is really 1023 bytes in size, it doesn't seem too > >>>unrealistic to allow 255 bytes of it for the mount_tag, or at the very > >>>least increase it from 32 to 128 ? > >>> > >> > >>Last time we discussed this Anthony wanted to keep the config space > >>usage minimal, hence we agreed on the size 32 bytes. > > > >Ping ? Anyone .... > > > >Does anyone have any clear information about the per-device config > >space we have available ? As above I'd really like us to raise > >the mount_tag length even just a little bit higher for QEMU 1.0, > >if we have the PCI config space available to play with. > > Yes, PCI PIO space is very small. I think 128 is even pushing it.
Odd, because I managed to pass through a 1023 byte path without appearing to have any trouble. Is the space per-device, or global to all devices. If the latter, I could understand the desire to keep it smaller. > Why not add a feature that exchanges the tag through another > mechanism such that there doesn't need to be a limit? It could be > as simple as adding an fsstat .L operation or something like that. That would require kernel side updates too I presume, so if that kind of change is the only option, I think I'll just have to change my app's code to cope with the current smaller limits for now. Regards, Daniel -- |: http://berrange.com -o- http://www.flickr.com/photos/dberrange/ :| |: http://libvirt.org -o- http://virt-manager.org :| |: http://autobuild.org -o- http://search.cpan.org/~danberr/ :| |: http://entangle-photo.org -o- http://live.gnome.org/gtk-vnc :|
