Subject: Re: mvneta: oops in __rcu_read_lock on mirabox

From: Willy Tarreau <[email-masked]>
Date: Wed, 18 Sep 2013 18:49:48 +0200

On Wed, Sep 18, 2013 at 06:35:49PM +0200, Thomas Petazzoni wrote:
> Dear Ethan Tuttle,
> 
> On Tue, 17 Sep 2013 23:30:56 -0700, Ethan Tuttle wrote:
> > On Mon, Sep 16, 2013 at 11:01 PM, Willy Tarreau <[email-masked]> wrote:
> > > Next step should be that you test both kernels to be sure.
> > 
> > Thanks for the kernel images, Willy.  I'm still experimenting but
> > initial results are strange: I haven't seen a crash from the -ethan
> > image you provided, nor by a kernel with that config that I built
> > myself.  The config is only different from my crashing config by a few
> > options.  So perhaps some combination of options prevents the crash.
> > I'll see if I can narrow it down.
> 
> A toolchain generating some crappy code maybe? Ethan, Willy, comparing
> your toolchain (compiler version, origin of the toolchain) could be
> interesting.

I thought about this but it looks suspicious, I don't see why the toolchain
would produce random bitflips.

My toolchain is a linaro 4.7 gcc into which I have added support for a
"pj4b" CPU target which is essentially the same as cortex-a9 plus support
for the IDIV instruction in thumb mode.

But I can send it to Ethan if that helps.

Willy