path: root/README
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authorIan Campbell <>2015-09-29 10:27:09 +0100
committerTom Rini <>2015-10-11 17:12:11 -0400
commite392b923ed6d6acff08b0a7aa5f457fff80fb0de (patch)
tree84be927a635cf5c7b67a83bde757e6fabbce700c /README
parent9950098e31004fdfb94c8c6ce3f4b27566a532bd (diff)
arndale: Apply Cortex-A15 errata #773022 and #774769
We run 4 Arndale boards in our automated test framework, they have been running quite happily for quite some time using a Debian Wheezy userspace. However when upgrading to a Debian Jessie we started seeing frequent segmentation faults from gcc when building the kernel, to the extent that it is unable to successfully build the kernel twice in a row, and often fails on the first attempt. Searching around I found which pointed towards and CPU Errata 773022 and 774769. This errata needs to be applied to all processors in an SMP system, meaning that the usual strategy of applying them in arch/arm/cpu/armv7/start.S is not appropriate (since that applies to the boot processor only). Instead we apply these errata in the secure monitor which is code that is traversed by all processors as they are brought up. The net affect on Arndale is that ACTLR changes from 0x40 to 0x2000042. I ran 17 kernel compile iterations overnight with no segfaults. Runtime testing was done on our v2014.10 based branch and forward ported (with only minimal and trivial contextual conflicts) to current master, where it has been build tested only. I suppose in theory these errata apply to any Exynos5250 based boards, but Arndale is the only one I have access to and I have therefore chosen to be conservative and only apply it there. Also, reorder CONFIG_ARM_ERRATA_794072 in README to make the list numerically sorted. Signed-off-by: Ian Campbell <>
Diffstat (limited to 'README')
1 files changed, 3 insertions, 1 deletions
diff --git a/README b/README
index c22b60b49b..0dc657d0a5 100644
--- a/README
+++ b/README
@@ -681,8 +681,10 @@ The following options need to be configured:
If set, the workarounds for these ARM errata are applied early
during U-Boot startup. Note that these options force the
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