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    SubjectRe: MIPS panic in 2.6.39 (bisected to 7eaceaccab5f)
    On 05/27/2011 09:00 AM, Ralf Baechle wrote:
    > On Fri, May 27, 2011 at 08:55:13AM +0100, Ralf Baechle wrote:
    >>> Have you guys been able to reproduce the problem?
    >> Staring at the disassembly was good enough, I think. The commit you
    >> bisected is restructuring some of the hardware probing code for Malta and
    >> seems to result in gcmp_present being set without _gcmp_base having been
    >> assigned, thus the null pointer dereference.
    > Can you test below patch? Thanks,
    > Ralf
    > Since af3a1f6f4813907e143f87030cde67a9971db533 the Malta code does no
    > longer probe for presence of GCMP if CMP is not configured. This means
    > that the variable gcmp_present well be left at its default value of -1
    > which normally is meant to indicate that GCMP has not yet been mmapped.
    > This non-zero value is now interpreted as GCMP being present resulting
    > in a write attempt to a GCMP register resulting in a crash.
    > Signed-off-by: Ralf Baechle <>

    patch patch patch...

    > diff --git a/arch/mips/mti-malta/malta-init.c b/arch/mips/mti-malta/malta-init.c
    > index 31180c3..4163d09e 100644
    > --- a/arch/mips/mti-malta/malta-init.c
    > +++ b/arch/mips/mti-malta/malta-init.c

    Your missing hunk at the top of this file is:

    @@ -29,6 +29,7 @@
    #include <asm/system.h>
    #include <asm/cacheflush.h>
    #include <asm/traps.h>
    +#include <asm/smp-ops.h>

    #include <asm/gcmpregs.h>
    #include <asm/mips-boards/prom.h>

    And then the patch works! Yay! Thank you.

    Signed-off-by: Rob Landley <>


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