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Old 09-30-2010, 02:33 PM
"Shilimkar, Santosh"
 
Default SRU: A workaround for highmem issue on OMAP4 platform

> -----Original Message-----
> From: kernel-team-bounces@lists.ubuntu.com [mailto:kernel-team-
> bounces@lists.ubuntu.com] On Behalf Of Bryan Wu
> Sent: Thursday, September 30, 2010 7:50 PM
> To: tim.gardner@canonical.com; ricardo.salveti@canonical.com;
> nicolas.pitre@linaro.org; kernel-team@lists.ubuntu.com
> Cc: ogra@canonical.com
> Subject: [Maverick] [ti-omap4] SRU: A workaround for highmem issue on
> OMAP4 platform
>
> 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:
> Generally when using highmem we can reproduce this issue quickly, with 10,
> 15
> minutes after started the kernel build. Using CONFIG_VMSPLIT_2G=y and
> Nicolas's
> VMALLOC_END patch, we can put 0 memory in highmem. But without highmem, we
> met
> another "Bad Mode" issue because of missing enabling errata fixing for L2
> controller PL310. As a result, 2G:2G split and errata fixing of PL310 is a
> workaround of this issue. We can fully use the whole 1G memory.
>
CONFIG_PL310_ERRATA_588369 errata is pretty much must for OMAP4 ES1.0. This
should always be enabled on OMAP4 ES1.0 not to see any undefined behaviour.

Regards,
Santosh

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Old 09-30-2010, 09:14 PM
"Dechesne, Nicolas"
 
Default SRU: A workaround for highmem issue on OMAP4 platform

Santosh,

> CONFIG_PL310_ERRATA_588369 errata is pretty much must for OMAP4 ES1.0. This
> should always be enabled on OMAP4 ES1.0 not to see any undefined behaviour.

but we are on ES2.0, not ES1.0. What is the impact of enabling this errata on ES2.0?

nicolas

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Old 10-01-2010, 03:56 AM
Ricardo Salveti de Araujo
 
Default SRU: A workaround for highmem issue on OMAP4 platform

On Thu, Sep 30, 2010 at 11:14:34PM +0200, Dechesne, Nicolas wrote:
> Santosh,
>
> > CONFIG_PL310_ERRATA_588369 errata is pretty much must for OMAP4 ES1.0. This
> > should always be enabled on OMAP4 ES1.0 not to see any undefined behaviour.
>
> but we are on ES2.0, not ES1.0. What is the impact of enabling this errata on ES2.0?

From the talk I had with Rob Clark:

<robclark> ndec / rsalveti: which errata?
<rsalveti> robclark: PL310_ERRATA_588369
<robclark> ok.. let me check
<robclark> rsalveti: ok.. this one seems to apply to the cortex-a9 IP, prior to r2p0
<robclark> (just need to check which rev on cortex is in es2.0)
<robclark> r1p2.. so keep the errata enabled

So it seems we're OK with it.

And during my tests I was finally able to run for more than 28 hours (14 builds)
without getting any errors, so it seems that it's finally better.

But unfortunatelly I can easily get errors when using highmem, no matter what
setup I'm using, so probably a different issue.

Good thing is that it seems we finally got a workaround to use 1GB at
Maverick.

Cheers,
--
Ricardo Salveti de Araujo

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