From: Suzuki.Poulose@arm•com (Suzuki K Poulose)
To: linux-arm-kernel@lists•infradead.org
Subject: [PATCH] arm64: erratum: Workaround for Kryo reserved system register read
Date: Fri, 8 Apr 2016 11:31:26 +0100 [thread overview]
Message-ID: <5707887E.3030406@arm.com> (raw)
In-Reply-To: <570786C9.6020804@arm.com>
On 08/04/16 11:24, Marc Zyngier wrote:
> On 08/04/16 10:58, Suzuki K Poulose wrote:
>> On 07/04/16 18:31, Marc Zyngier wrote:
>>
>>>> + All system register encodings above use the form
>>>> +
>>>> + Op0, Op1, CRn, CRm, Op2.
>>>> +
>>>> + Note that some of the encodings listed above include
>>>> + the system register space reserved for the following
>>>> + identification registers which may appear in future revisions
>>>> + of the ARM architecture beyond ARMv8.0.
>>>> + This space includes:
>>>> + ID_AA64PFR[2-7]_EL1
>>>> + ID_AA64DFR[2-3]_EL1
>>>> + ID_AA64AFR[2-3]_EL1
>>>> + ID_AA64ISAR[2-7]_EL1
>>>> + ID_AA64MMFR[2-7]_EL1
>>
>>
>> AFAIK, the id space is unassigned. So the naming above could cause confusion
>> if the register is named something else.
>
> It is reserved *at the moment*, but already has a defined behaviour. My
Absolutely, they do need to be RAZ. My point was assigning names to the reserved
space where the names are unassigned.
> worry is that when some new architecture revision comes around, we start
> using these registers without thinking much about it (because we should
> be able to). At this point, your SoC will catch fire and nobody will
> have a clue about the problem because it is not apparent in the code.
>
> I'd really like to see something a bit more forward looking that covers
> that space for good.
I agree, the patch definitely needs to take care of handling the entire space.
Cheers
Suzuki
next prev parent reply other threads:[~2016-04-08 10:31 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-04-07 15:54 [PATCH] arm64: erratum: Workaround for Kryo reserved system register read Naveen Kaje
2016-04-07 17:31 ` Marc Zyngier
2016-04-08 9:58 ` Suzuki K Poulose
2016-04-08 10:24 ` Marc Zyngier
2016-04-08 10:31 ` Suzuki K Poulose [this message]
2016-04-08 11:00 ` Marc Zyngier
2016-04-11 6:49 ` James Morse
2016-04-11 10:06 ` Will Deacon
2016-04-12 13:27 ` Catalin Marinas
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