Re: Grant Table Network Issues

[Michael Vrable <mvrable@cs.ucsd.edu>]

On Sun, Aug 14, 2005 at 04:59:53PM +0100, Ian Pratt wrote:
> > On Sun, Aug 14, 2005 at 08:39:53AM -0700, Michael Vrable wrote:
> > > Allocating the arrays statically fixes the problem for me.  
> > Steve Hand 
> > > says he'll likely be committing a fix soon.
> > 
> > Never mind; catching up on the changes to xen-unstable.hg, I 
> > see that you've already committed a fix.  Thanks.
> 
> Michael, if this fix is working fine for you, I minded to enable them in
> the default config... 

I haven't tested this particular commit, since I'm currently using a
testing a version of Xen that is patched to run unprivileged domains in
shadow translated mode, with grant-table based networking.  However, the
equivalent patch in my tree has fixed my networking stability issues.

There are still a few robustness issues to work on.  For example, the
BUG() when grant table donate operations fail in net_rx_action, which
can legitimately happen if the unprivileged domain hasn't set up its
grant tables properly.  I haven't seen this come up in normal use, but
does need to be fixed before the final release, since it will let an
unprivileged domain crash domain-0.  (I have seen it in my work, but
then I'm not doing normal things with unprivileged domains.)

I'd either vote for enabling grant tables now to get some wider testing,
but with a warning that some corner cases still need some work, or do a
check of the places that netback calls BUG() first.

--Michael Vrable