From: will.deacon@arm.com (Will Deacon)
To: linux-arm-kernel@lists.infradead.org
Subject: bug with 3.4.6, 3.5.3, 3.6.1
Date: Thu, 11 Oct 2012 14:59:05 +0100 [thread overview]
Message-ID: <20121011135905.GL30598@mudshark.cambridge.arm.com> (raw)
In-Reply-To: <5076CA56.3020006@xenomai.org>
On Thu, Oct 11, 2012 at 02:32:06PM +0100, Gilles Chanteperdrix wrote:
> On 10/11/2012 12:36 PM, Will Deacon wrote:
> > On Thu, Oct 11, 2012 at 06:46:35AM +0100, Gilles Chanteperdrix wrote:
> >> Hi,
> >
> > Hi Gilles,
> >
> >> when booting Linux v3.4.6, v3.5.3, or v3.6.1 on a pandaboard with an
> >> OMAP4430 ES2.1, compiled with the following configuration:
> >> http://xenomai.org/~gch/config-panda
> >>
> >> I get the bug below after mounting the root filesystem.
> >>
> >> CONFIG_VMSPLIT_2G and CONFIG_THUMB2_KERNEL disabled seems to be the
> >> combination which triggers the bug.
> >>
> >> With this configuration, it seems the init_mm.mm_count incrementation
> >> done at the beginning of secondary_start_kernel() is "lost" after the
> >> calls to cpu_switch_mm() and local_flush_tlb().
> >>
> >> Modifying the secondary_startup() function in head.S to pass the
> >> swapper pgdir instead of the idmap pgdir in r4 also avoids the issue.
> >
> > What's your PHYS_OFFSET? I suspect it's >= 2GB, in which case I have some
> > ideas about this problem.
>
> Yes, according to /proc/iomem:
> 80000000-bfefffff : System RAM
> 80008000-80339fff : Kernel code
> 80364000-803c52e7 : Kernel data
>
> So, PHYS_OFFSET is 0x80000000 that is, 2GB.
Argh, then there's something fishy with the interaction between the idmap
and swapper. The overwritten entries *should* be identical, but something is
causing us to corrupt the initial tables from pgd_alloc(). Perhaps something
to do with us mapping in sections...
I'll have to do some digging and get back to you.
Cheers,
Will
next prev parent reply other threads:[~2012-10-11 13:59 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-11 5:46 bug with 3.4.6, 3.5.3, 3.6.1 Gilles Chanteperdrix
2012-10-11 10:36 ` Will Deacon
2012-10-11 12:54 ` Gilles Chanteperdrix
2012-10-11 13:32 ` Gilles Chanteperdrix
2012-10-11 13:59 ` Will Deacon [this message]
2012-10-11 14:01 ` Gilles Chanteperdrix
2012-10-11 14:03 ` Will Deacon
2012-10-11 19:50 ` Will Deacon
2012-10-11 20:58 ` Gilles Chanteperdrix
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