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

[Bryan Wu]

On Fri, Sep 24, 2010 at 3:50 PM, Tim Gardner <tim.gardner at canonical.com> wrote:
> On 09/24/2010 11:21 AM, Bryan Wu wrote:
>>
>> SRU Justification:
>>
>> Impact:
>> There is a critical highmem issue on our latest OMAP4 ES2.0 platform. When
>> we
>> build kernel package natively on ES2.0 platform with mem=1G and highmem
>> enabled, we will meet 'Bus Error' corruption from gcc shortly. And
>> 'Unhandled
>> imprecised external abort' kernel oops messages. Then the whole system
>> will be
>> very instable.
>>
>> Fix: After some debugging, this issue is related to highmem. If we don't
>> use
>> mem=1G (no memory in highmem), the corruption is gone. So there is a
>> workaround
>> which is CONFIG_VMSPLIT_2G=y. So user and kernel memory split is 2G:2G
>> instead
>> of default 3G:1G. We can use all the 1G memory on ES2.0, but don't put any
>> memory in highmem. As a result, the issue is gone.
>>
>> Testcase: Add kernel boot command line mem=1G, build kernel package on
>> ES2.0
>> hardware after booting the kernel. The issue is supposed to be gone with
>> 2G:2G
>> split config.
>>
>> A testing kernel is also here:
>> http://people.canonical.com/~roc/kernel/lp633227/
>>
>> Notes: the VMALLOC_END value is wrong in mach-omap2, Nicolas Pitre posted
>> a fixing
>> patch to upstream, which is required in this workaround.
>>
>> BugLink: http://bugs.launchpad.net/bugs/#633227
>>
>> Plese consider pull from
>>  git://kernel.ubuntu.com/roc/ubuntu-maverick lp633227
>>
>> Bryan Wu (1):
>>   UBUNTU: [Config] Enable CONFIG_VMSPLIT_2G=y for OMAP4
>>
>> Nicolas Pitre (1):
>>   ARM: do not define VMALLOC_END relative to PAGE_OFFSET
>>
>>  arch/arm/mach-aaec2000/include/mach/vmalloc.h   |    2 +-
>>  arch/arm/mach-bcmring/include/mach/vmalloc.h    |    2 +-
>>  arch/arm/mach-clps711x/include/mach/vmalloc.h   |    2 +-
>>  arch/arm/mach-ebsa110/include/mach/vmalloc.h    |    2 +-
>>  arch/arm/mach-footbridge/include/mach/vmalloc.h |    2 +-
>>  arch/arm/mach-h720x/include/mach/vmalloc.h      |    2 +-
>>  arch/arm/mach-integrator/include/mach/vmalloc.h |    2 +-
>>  arch/arm/mach-msm/include/mach/vmalloc.h        |    2 +-
>>  arch/arm/mach-netx/include/mach/vmalloc.h       |    2 +-
>>  arch/arm/mach-omap1/include/mach/vmalloc.h      |    2 +-
>>  arch/arm/mach-omap2/include/mach/vmalloc.h      |    2 +-
>>  arch/arm/mach-pnx4008/include/mach/vmalloc.h    |    2 +-
>>  arch/arm/mach-rpc/include/mach/vmalloc.h        |    2 +-
>>  arch/arm/mach-shark/include/mach/vmalloc.h      |    2 +-
>>  arch/arm/mach-versatile/include/mach/vmalloc.h  |    2 +-
>>  debian.ti-omap4/config/config.common.ubuntu     |    6 +++---
>>  16 files changed, 18 insertions(+), 18 deletions(-)
>>
>
> So, what do you want me to do? Ricardo is saying this workaround is not
> sufficient.
>

Please ignore this pull request. We are working on it.

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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