[uml-devel] Panic with slirp transport and gcc 3.3

[Matt Zimmerman <mdz@debian.org>]

On Wed, Jan 07, 2004 at 11:07:18PM -0800, Matt Zimmerman wrote:

> On Mon, Jan 05, 2004 at 09:58:32PM -0500, Jeff Dike wrote:
> 
> > mdz@debian.org said:
> > > It turns out that this problem seems to be due to compiler
> > > incompatibility. UML had been built with gcc 2.95 due to old breakage,
> > > and when built with gcc 3.3 (as glibc is), everything starts working
> > > again.  My suspicion is that this is due to certain recent changes in
> > > pthreads.
> > 
> > Is it your opinion that there's no problem in UML itself?  Having a field
> > in the sigcontext getting magically munged is somewhat worrying.  I'd be 
> > happier knowing what exactly was happening so I can be sure this wasn't
> > exposing some subtle UML bug.
> 
> I was not able to come to a satisfactory conclusion as to the origin of the
> problem, and once I found a solution, I stopped looking.  I'm copying
> debian-gcc and debian-glibc in case they're interested.
> 
> Summary for debian-{gcc,glibc}:
> 
> UML built with gcc-2.95 fails to run correctly on a current unstable system
> with a 2.4 kernel.  The symptoms are very strange; This started to happen recently; UML had been building
> with gcc 2.95 successfully for over 9 months now with no problems.
> 
> Details are here: http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=224431

By the way, the original reason why I started building UML with gcc-2.95 was
because building with 3.x broke the slirp transport like so:

Kernel panic: read of switch_pipe failed, errno = 9

errno 9 is EBADF.  I never did find the real cause of that bug, but it has
resurfaced now that I am building with gcc 3.3 again to fix the other, worse
bug.  I would be interested to know if anyone else has run into it.  More
information is here:

http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=176485&archive=yes

-- 
 - mdz


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