[Maverick] [ti-omap4] SRU: A workaround for highmem issue on OMAP4 platform

[Bryan Wu]

On Mon, Sep 27, 2010 at 12:31 AM, Nicolas Pitre
<nicolas.pitre at canonical.com> wrote:
> On Sun, 26 Sep 2010, Bryan Wu wrote:
>
>> On Sun, Sep 26, 2010 at 11:01 PM, Nicolas Pitre
>> <nicolas.pitre at canonical.com> wrote:
>> > On Sun, 26 Sep 2010, Ricardo Salveti de Araujo wrote:
>> >
>> >> On Fri, Sep 24, 2010 at 03:04:10AM -0300, Ricardo Salveti de Araujo wrote:
>> >> > Will also test it with only one cpu to see if this could be realted with SMP
>> >> > issues.
>> >>
>> >> Ok, tested the same kernel but running with only one CPU, for 40 hours (what gave me
>> >> 15 builds), and went all fine, without any errors at both userspace and kernelspace.
>> >>
>> >> So it seems that this data abort exception could be related with concurrency and
>> >> SMP support at our kernel.
>> >
>> > Right.  So I'd suggest you keep highmem off, and 2g:2g on (with the
>> > VMALLOC_END fix), then try to reliably reproduce the issue with that
>> > configuration and fix it before involving highmem again.  While highmem
>> > may make the problem more visible, it also brings a set of added
>> > complexity of its own which would make the tracking of the issue much
>> > harder.
>> >
>> >
>> > Nicolas
>> >
>>
>> I disabled CONFIG_CACHE_L2X0 L2 cache controller for omap4. So far for
>> the SMP kernel with mem=1G, kernel building is running correctly.
>> I will test more. It looks like L2 cache controlling has some issue.
>
> That's with or without highmem involved?
>
>

It's with highmem, but finally it still fails with message like this:
"Unhandled fault: imprecise external abort (0x1406) at 0x400b0000"

Thanks,
-- 
Bryan Wu <bryan.wu at canonical.com>
Kernel Developer    +86.138-1617-6545 Mobile
Ubuntu Kernel Team
Canonical Ltd.      www.canonical.com
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