Messages in this thread | | | Date | Fri, 23 Feb 2018 17:58:22 +0000 | From | James Morse <> | Subject | Re: [PATCH] arm64: rename the function arm64_is_ras_serror() to avoid confusion |
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Hi Dongjiu Geng,
On 22/02/18 18:02, Dongjiu Geng wrote: > The RAS SError Syndrome can be Implementation-Defined, > arm64_is_ras_serror() is used to judge whether it is RAS SError, > but arm64_is_ras_serror() does not include this judgement. In order > to avoid function name confusion, we rename the arm64_is_ras_serror() > to arm64_is_categorized_ras_serror(), this function is used to > judge whether it is categorized RAS Serror.
I don't see how 'categorized' is relevant. The most significant ISS bit is used to determine if this is an IMP-DEF ESR, or one that uses the architected layout.
DFSC of zero means uncategorised. What should we do with an uncategorised SError?
From 2.4.3 "ESB and other physical errors" of [0] | It is IMPLEMENTATION DEFINED whether [..]uncategorized SError interrupts | are containable or Uncontainable, and whether they can be synchronized by an | Error Synchronization Barrier.
We treat uncategorized as uncontainable as that's the worst thing it could be.
On aarch32 uncontainable and uncategorized even share an encoding. (AET:00 in G7.2.43 "DFSR, Data Fault Status Register", 'state of the PE after taking the SError interrupt exception')
> Change some code notes, unrecoverable RAS errors is imprecise, but > Recoverable RAS errors is precise.
Unrecoverable and Recoverable (but we don't know where it is) are both grouped into 'can't make progress'. The comment says: | The exception may have been imprecise. because one of those two is imprecise.
If anyone cares which one is which, they can read the spec.
I expect this code will one day be replaced with proper kernel-first support, its only here to avoid panic()ing due to corrected errors.
Thanks,
James
[0] https://static.docs.arm.com/ddi0587/a/RAS%20Extension-release%20candidate_march_29.pdf
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