TLB Miss booting linux kernel on ppc 405

Ricardo Ayres Severo severo.ricardo at gmail.com
Thu Feb 14 04:38:24 EST 2008


I tracked the kernel execution using step one instruction (si) on gdb
and matching the jumps with the System.map.
It is a Data TLB Miss and this is the register dump after the miss occurs:

    r1: 00502090
    r2: 0000000f
    r3: c00003c0
    r4: c0000000
    r5: 00000000
    r6: 00000000
    r7: 74747955
    r8: 4c302c39
    r9: 00000000
    pc: 00001100
    lr: 00000018

Now I'm checking the PPC cache configurations on XPS, because when
treating the DTLB Miss Exception a Machine Check Exception occurs when
it works with L1. Does this makes sense or am I confusing things?

Thanks,

On Feb 13, 2008 3:17 PM, David Baird <dhbaird at gmail.com> wrote:
> On Feb 13, 2008 9:50 AM, Ricardo Ayres Severo <severo.ricardo at gmail.com> wrote:
> > Hi All,
> >
> > I'm using kernel 2.6.24 and when it comes to line 826 on the file
> > arch/ppc/kernel/head_4xx.S it gives a TLB Miss.
> >
> > arch/ppc/kernel/head_4xx.S
> > 823 start_here:
> > 824
> > 825         /* ptr to current */
> > 826         lis    r2,init_task at h
> > 827         ori    r2,r2,init_task at l
>
> I am just curious: how did you find that you have TLB miss on that
> line?  Is it an Instruction TLB miss or a Data TLB miss?
>
> Can you paste a dump of your registers (in XMD, rrd and srrd)?
>
> I was having TLB misses awhile back due to some other problems, but
> never had any on that line though.
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-- 
Ricardo Ayres Severo <severo.ricardo at gmail.com>


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