From: Scott Wood <oss@buserror.net>
To: David Lamparter <equinox@diac24.net>
Cc: Scott Wood <swood@redhat.com>,
linuxppc-dev@lists.ozlabs.org, York Sun <york.sun@nxp.com>
Subject: Re: [PATCH ppc-next] powerpc/fsl-booke: don't load early TLB at once
Date: Sat, 22 Sep 2018 00:45:16 -0500 [thread overview]
Message-ID: <20180922054516.GA19015@home.buserror.net> (raw)
In-Reply-To: <20180921010019.GL487685@eidolon.nox.tf>
On Fri, Sep 21, 2018 at 03:00:19AM +0200, David Lamparter wrote:
> On Thu, Sep 20, 2018 at 07:31:33PM -0500, Scott Wood wrote:
> > Do you have a JTAG that can be used to find out where it's hanging? If
> > not, I can try to get early debug working (needs an early IOMMU mapping).
s/IOMMU mapping/MMU mapping for MMIO/ :-P
> I only have JTAG tools for ARM chips available; hardware wise I could
> probably solder up an adapter but software wise I have absoutely no clue
> how to fire up a session on anything PPC... I'm a novice openocd user,
> that's it.
>
> > York, can you try booting the latest kernel on p4080ds?
>
> d9e1831a42 has been around for quite some time, 4.4 already has it. I
> was a bit surprised noone has run into this, but then again P4080 is not
> exactly the most recent/interesting hardware.
I don't suppose you're running a relocatable kernel at a non-zero
address, and/or are running in an environment that sets
HID0[EN_L2MMU_MHD] (neither standard U-boot nor Linux sets this bit,
though they probably should)? On 32-bit, we're already running in an AS1
trampoline when loadcam_multi() is called, but loadcam_multi() sets up
its own. This happens to not be catastrophic in standard scenarios, but
it does add a duplicate TLB entry, and we return to AS0 sooner than
expected. I think your patch, plus ifdefs to make the change 32-bit
only, is the appropriate fix.
I also got an earlier udbg for e500 working (and happened to decide to
test it with a relocatable kernel); I'll send that out once I've cleaned
it up (or sooner with the extra TLB dumping included if the above doesn't
explain why you're hitting this bug).
-Scott
next prev parent reply other threads:[~2018-09-22 5:47 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-09-20 22:48 [PATCH ppc-next] powerpc/fsl-booke: don't load early TLB at once David Lamparter
2018-09-21 0:31 ` Scott Wood
2018-09-21 1:00 ` David Lamparter
2018-09-22 5:45 ` Scott Wood [this message]
2018-10-01 14:26 ` David Lamparter
2018-09-21 17:40 ` York Sun
2018-09-21 17:47 ` Scott Wood
2018-09-21 18:07 ` York Sun
2018-10-01 13:51 ` David Lamparter
2018-09-24 5:15 ` Michael Ellerman
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