From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Linus Torvalds <torvalds@osdl.org>
Cc: Linux Kernel list <linux-kernel@vger.kernel.org>,
Paul Mackerras <paulus@samba.org>,
"Antonino A. Daplas" <adaplas@hotpop.com>
Subject: Re: Current bk on ppc32: kernel text corruption
Date: Sun, 20 Feb 2005 10:32:12 +1100 [thread overview]
Message-ID: <1108855933.5584.2.camel@gaston> (raw)
In-Reply-To: <1108710554.5587.1.camel@gaston>
On Fri, 2005-02-18 at 18:09 +1100, Benjamin Herrenschmidt wrote:
> Ok, we may not be over with memory corruption bugs yet. ppc64 now seem
> stable running LTP overnight, but my laptop has a page of kernel .text
> replaced with zero's as soon as I launch X (and just X, no need to launc
> the whole desktop environment).
>
> I suspect remap_pfn_range() but I haven't checked yet.
Ok, I found it. It's a bug that was there forever it seems, where
radeonfb accel ops may corrupt kernel memory (via bus master from the
radeon chip) when switching back from X, due to X remapping some areas
of the card vs. fbcon calling some radeonfb accel ops before radeonfb
has a chance to re-initialize the chip (when switching back from X).
I'm cooking a workaround patch for 2.6.11, will be ready as soon as I
have tested. Proper fix is to make sure fbcon never calls any fbdev
accel op before the chip has been properly restored (by a set_var call),
but that is beyond the scope of 2.6.11 I suppose...
Ben.
next prev parent reply other threads:[~2005-02-19 23:33 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-02-18 7:09 Current bk on ppc32: kernel text corruption Benjamin Herrenschmidt
2005-02-19 23:32 ` Benjamin Herrenschmidt [this message]
2005-02-19 23:45 ` [PATCH] radeonfb: Workaround memory corruption accel problem Benjamin Herrenschmidt
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