From: sudeep.holla@arm•com (Sudeep Holla)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH] arm64: Add L2 cache topology to ARM Ltd boards/models
Date: Mon, 16 Feb 2015 09:56:21 +0000 [thread overview]
Message-ID: <54E1BEC5.5070009@arm.com> (raw)
In-Reply-To: <20150212140702.GF1522@leverpostej>
Hi Mark,
On 12/02/15 14:07, Mark Rutland wrote:
> Hi,
>
> On Wed, Jan 21, 2015 at 04:46:32PM +0000, Mark Rutland wrote:
>> On Wed, Jan 21, 2015 at 12:02:30PM +0000, Sudeep Holla wrote:
>>> Commit 5d425c18653731af6 ("arm64: kernel: add support for cpu
>>> cache information") adds cacheinfo support for ARM64. Since
>>> there's no architectural way of detecting the cpus that share
>>> particular cache, device tree can be used and the core cacheinfo
>>> already supports the same.
>>
>> This still leaves the possibility that misleading information is
>> exposed for systems from other vendors. I've made a quick attempt
>> to Cc the authors of other arm64 dts here.
>>
>> Given that in the absence of these nodes we can't derive a complete
>> view of the cache hierarchy, shouldn't we only expose the cacheinfo
>> when we have these nodes and can therefore produce correct values?
>
> I'm still rather concerned about exposing misleading cache info in
> this manner. Is there no way we can limit the exposure of this
> information to those cases where we actually have the information?
>
Yes I have a patch to check all the device nodes in the cache hierarchy
before initializing the sysfs. So cacheinfo won't be setup if all the
device nodes aren't found(at-least on architecture like ARM/ARM64 which
depends on DT). I will post it soon, was waiting for a week so that it's
not lost during merge window.
> Do we know if/how this will work for ACPI systems?
>
It should be similar to DT i.e. the hierarchy must be completely
detected through ACPI tables/methods, but I have not thought of
implementation specifics yet.
Regards,
Sudeep
next prev parent reply other threads:[~2015-02-16 9:56 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-01-21 12:02 [PATCH] arm64: Add L2 cache topology to ARM Ltd boards/models Sudeep Holla
2015-01-21 14:43 ` Arnd Bergmann
2015-01-21 15:48 ` Catalin Marinas
2015-02-24 15:14 ` Sudeep Holla
2015-02-25 16:14 ` Arnd Bergmann
2015-02-25 18:19 ` Sudeep Holla
2015-01-21 16:46 ` Mark Rutland
2015-02-12 14:07 ` Mark Rutland
2015-02-13 2:52 ` Lorenzo Pieralisi
2015-02-16 9:56 ` Sudeep Holla [this message]
2015-02-16 10:19 ` Mark Rutland
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