Booting L4Re on the CI20: Panic in sigma0

Paul Boddie paul at boddie.org.uk
Fri Jul 21 00:43:51 CEST 2017


On Friday 21. July 2017 00.06.27 Adam Lackorzynski wrote:
> On Thu Jul 20, 2017 at 22:10:48 +0200, Paul Boddie wrote:
> > 
> > While handling this page fault, there appears to be another page fault in
> > the kernel (at 0x80019c8c). This latter fault can't be handled (as
> > discussed below) and so the original exception is eventually exposed in
> > L4Re with the confused mix of details noted above.
> > 
> > The unlikely address of 0x8 reported by L4Re may be related to the kernel
> > fault address of 0xc, which according to the above details occurs in the
> > following code (found in Ram_quota::alloc):
> 
> That looks like you should use the patch in
> http://os.inf.tu-dresden.de/pipermail/l4-hackers/2017/008005.html

Well, that fixed it. Thanks for pointing it out!

I'll have to see what that patch actually does, I guess. The explanation from 
the referenced message seems to be that the compiler outmanoeuvred the authors 
of the code, so I suppose this is my punishment for using a newer compiler.

Should the patch be something that is available via the Subversion repository 
or is it a tentative change that hasn't been fully tested yet?

Anyway, I can now hopefully return to the program I thought I'd be testing on 
Wednesday and see what mistakes I've made in my driver code.

Thanks once again,

Paul



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