From: "Mark A. Greer" <mgreer@mvista.com>
To: Adrian Cox <adrian@humboldt.co.uk>
Cc: linuxppc-dev@lists.linuxppc.org
Subject: Re: [PATCH] Workaround for 745x data corruption bug
Date: Mon, 02 Aug 2004 11:20:30 -0700 [thread overview]
Message-ID: <410E85EE.8050707@mvista.com> (raw)
In-Reply-To: <1091291276.987.57.camel@localhost>
[-- Attachment #1: Type: text/plain, Size: 792 bytes --]
Adrian Cox wrote:
>Recently released errata documents show a new bug in all 745x family
>processors. This can cause data corruption when memory is mapped
>non-coherent and one of these conditions is true:
>1) L2 hardware prefetch is enabled (as it is in Linux)
>2) instructions and data are fetched from the same or adjacent cache
>lines.
>
>The attached patch adds a workaround, by setting CPU_FTR_NEED_COHERENT
>on all 745x processors.
>
Well that sucks (the bug, not the patch :). Many people like to turn
off coherency when using Marvell host bridges b/c they struggle
performance-wise with coherency on (at least on some versions).
One change to the patch, though. According to the 7447/7457 errata doc,
rev 1.2 doesn't have the bug. The attached patch accounts for that.
Mark
--
[-- Attachment #2: coherent2.patch --]
[-- Type: text/plain, Size: 537 bytes --]
===== arch/ppc/kernel/cputable.c 1.25 vs edited =====
--- 1.25/arch/ppc/kernel/cputable.c 2004-08-01 17:30:29 -07:00
+++ edited/arch/ppc/kernel/cputable.c 2004-08-02 11:12:37 -07:00
@@ -352,7 +352,7 @@
CPU_FTR_SPLIT_ID_CACHE | CPU_FTR_USE_TB | CPU_FTR_CAN_NAP |
CPU_FTR_L2CR | CPU_FTR_ALTIVEC_COMP | CPU_FTR_L3CR |
CPU_FTR_HPTE_TABLE | CPU_FTR_SPEC7450 | CPU_FTR_NAP_DISABLE_L2_PR |
- CPU_FTR_HAS_HIGH_BATS | CPU_FTR_NEED_COHERENT,
+ CPU_FTR_HAS_HIGH_BATS,
COMMON_PPC | PPC_FEATURE_ALTIVEC_COMP,
32, 32,
__setup_cpu_745x
next prev parent reply other threads:[~2004-08-02 18:20 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2004-07-31 16:27 [PATCH] Workaround for 745x data corruption bug Adrian Cox
2004-08-01 2:53 ` Benjamin Herrenschmidt
2004-08-02 15:20 ` Kumar Gala
2004-08-02 21:40 ` Benjamin Herrenschmidt
2004-08-02 18:20 ` Mark A. Greer [this message]
2004-08-02 21:47 ` Sven Luther
2004-08-03 13:17 ` Brian Waite
2004-08-03 21:55 ` Mark A. Greer
2004-08-04 14:37 ` Brian Waite
2004-08-04 17:55 ` Mark A. Greer
2004-08-04 20:39 ` Adrian Cox
2004-08-04 0:45 ` Benjamin Herrenschmidt
2004-08-04 17:38 ` Brian Waite
2004-08-04 22:43 ` Benjamin Herrenschmidt
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