[PATCHv2,1/1] ARM: improve Cortex A8/A9 errata help text
Commit Message
Docuemnt that !ARCH_MULTIPLATFORM is necessary because accessing
the the errata workaround registers may not work in non-secure
mode and mention that these erratas should be applied by the
bootloader instead.
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
---
Changes since RFCv1
* https://lore.kernel.org/all/20221209182000.549179-1-sebastian.reichel@collabora.com/
* update help text instead of removing !ARCH_MULTIPLATFORM
---
arch/arm/Kconfig | 26 +++++++++++++++++++++-----
1 file changed, 21 insertions(+), 5 deletions(-)
Comments
Il 14/12/22 18:53, Sebastian Reichel ha scritto:
> Docuemnt that !ARCH_MULTIPLATFORM is necessary because accessing
> the the errata workaround registers may not work in non-secure
> mode and mention that these erratas should be applied by the
> bootloader instead.
>
> Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Followed the discussion... adding this information makes a lot of sense
and it's definitely helpful for developers (especially when some platform
encounters *strange* issues..)
So,
Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com>
Cheers!
On Wed, Dec 14, 2022, at 18:53, Sebastian Reichel wrote:
> Docuemnt that !ARCH_MULTIPLATFORM is necessary because accessing
> the the errata workaround registers may not work in non-secure
> mode and mention that these erratas should be applied by the
> bootloader instead.
>
> Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
Reviewed-by: Arnd Bergmann <arnd@arndb.de>
Can you add this to Russell's patch tracker?
Arnd
Hi,
On Thu, Dec 15, 2022 at 02:58:43PM +0100, Arnd Bergmann wrote:
> On Wed, Dec 14, 2022, at 18:53, Sebastian Reichel wrote:
> > Docuemnt that !ARCH_MULTIPLATFORM is necessary because accessing
> > the the errata workaround registers may not work in non-secure
> > mode and mention that these erratas should be applied by the
> > bootloader instead.
> >
> > Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>
>
> Reviewed-by: Arnd Bergmann <arnd@arndb.de>
>
> Can you add this to Russell's patch tracker?
https://www.armlinux.org.uk/developer/patches/viewpatch.php?id=9281/1
-- Sebastian
@@ -656,7 +656,9 @@ config ARM_ERRATA_458693
hazard might then cause a processor deadlock. The workaround enables
the L1 caching of the NEON accesses and disables the PLD instruction
in the ACTLR register. Note that setting specific bits in the ACTLR
- register may not be available in non-secure mode.
+ register may not be available in non-secure mode and thus is not
+ available on a multiplatform kernel. This should be applied by the
+ bootloader instead.
config ARM_ERRATA_460075
bool "ARM errata: Data written to the L2 cache can be overwritten with stale data"
@@ -669,7 +671,9 @@ config ARM_ERRATA_460075
and overwritten with stale memory contents from external memory. The
workaround disables the write-allocate mode for the L2 cache via the
ACTLR register. Note that setting specific bits in the ACTLR register
- may not be available in non-secure mode.
+ may not be available in non-secure mode and thus is not available on
+ a multiplatform kernel. This should be applied by the bootloader
+ instead.
config ARM_ERRATA_742230
bool "ARM errata: DMB operation may be faulty"
@@ -682,7 +686,10 @@ config ARM_ERRATA_742230
ordering of the two writes. This workaround sets a specific bit in
the diagnostic register of the Cortex-A9 which causes the DMB
instruction to behave as a DSB, ensuring the correct behaviour of
- the two writes.
+ the two writes. Note that setting specific bits in the diagnostics
+ register may not be available in non-secure mode and thus is not
+ available on a multiplatform kernel. This should be applied by the
+ bootloader instead.
config ARM_ERRATA_742231
bool "ARM errata: Incorrect hazard handling in the SCU may lead to data corruption"
@@ -697,7 +704,10 @@ config ARM_ERRATA_742231
replaced from one of the CPUs at the same time as another CPU is
accessing it. This workaround sets specific bits in the diagnostic
register of the Cortex-A9 which reduces the linefill issuing
- capabilities of the processor.
+ capabilities of the processor. Note that setting specific bits in the
+ diagnostics register may not be available in non-secure mode and thus
+ is not available on a multiplatform kernel. This should be applied by
+ the bootloader instead.
config ARM_ERRATA_643719
bool "ARM errata: LoUIS bit field in CLIDR register is incorrect"
@@ -734,7 +744,9 @@ config ARM_ERRATA_743622
register of the Cortex-A9 which disables the Store Buffer
optimisation, preventing the defect from occurring. This has no
visible impact on the overall performance or power consumption of the
- processor.
+ processor. Note that setting specific bits in the diagnostics register
+ may not be available in non-secure mode and thus is not available on a
+ multiplatform kernel. This should be applied by the bootloader instead.
config ARM_ERRATA_751472
bool "ARM errata: Interrupted ICIALLUIS may prevent completion of broadcasted operation"
@@ -746,6 +758,10 @@ config ARM_ERRATA_751472
completion of a following broadcasted operation if the second
operation is received by a CPU before the ICIALLUIS has completed,
potentially leading to corrupted entries in the cache or TLB.
+ Note that setting specific bits in the diagnostics register may
+ not be available in non-secure mode and thus is not available on
+ a multiplatform kernel. This should be applied by the bootloader
+ instead.
config ARM_ERRATA_754322
bool "ARM errata: possible faulty MMU translations following an ASID switch"