> X-Authentication-Warning: wheel.tiac.net: Host localhost didn't use HELO protocol
> Cc: gnats-bugs@netbsd.org, gnats-admin@netbsd.org, spberry@iastate.edu,
>         tron@lyssa.owl.de, banshee@gabriella.resort.com, perry@piermont.com,
>         port-i386@netbsd.org
> Date: Sat, 06 Jan 1996 12:49:57 -0500
> From: "Gary D. Duzan" <gary@wheel.tiac.net>
> 
> In Message <199601061734.MAA19823@amsterdam.lcs.mit.edu> ,
>    David Mazieres <dm@amsterdam.lcs.mit.edu> wrote:
> 
> =>I was having trouble with my ppp interface hanging after a while.  It
> =>turns out this is caused not by any changes in the kernel sources but
> =>by compiling the kernel with gcc-2.7.2.  When I recompile the kernel
> =>with 2.4.5, the problem goes away.
> 
>    True, but that begs the question, is it a gcc 2.7.2 bug or a
> kernel bug that happens to be triggered by gcc 2.7.2 or perhaps
> points to some flags that we need to give to gcc 2.7.2 to compile
> the kernel.

Oops, please don't CC the gnats addresses on the replies.  Sorry, I
should have sent two separate messages.

At any rate, gcc-2.7.2 is very good about optimizing multiple
reads/writes to/from the same memory location.  This can lead to
concurrency problems when you really do need to read twice.  One way
to test for this would be with the "-fvolatile-global" flag of gcc.
If that makes the problem go away, then it is likely to be a bug in
the kernel.

David