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: > > On Thu, Sep 29, 2011 at 08:23:49PM +0530, Aneesh Kumar K.V wrote: > > > On Thu, 29 Sep 2011 11:34:21 +0100, "Daniel P. Berrange" > > > <berra...@redhat.com> wrote: > > > > From: "Daniel P. Berrange" <berra...@redhat.com> > > > > > > > > The Linux guest kernel does not appear to have a problem handling > > > > a mount_tag larger than 32 bytes. Increase the limit to 255 bytes, > > > > though perhaps it can be made larger still, or not limited at all ? > > > > > > > > Tested with a 3.0.4 kernel and a mount_tag 255 bytes in length. > > > > > > > > * hw/9pfs/virtio-9p.h: Change MAX_TAG_LEN to 255 > > > > > > > > > mount_tag is passed via pci config space, do we want to have 255 bytes > > > out of that for device identification. > > > > How big is the config space available for each 9pfs device and what > > other info does it need to keep there ? > > Does anyone have an clear answer for this ? > > 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. Anthony, Any comments ? -aneesh
