From: Christophe Leroy <christophe.leroy@c-s.fr>
To: Michael Ellerman <mpe@ellerman.id.au>,
"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
npiggin@gmail.com, paulus@samba.org
Cc: linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH v2] powerpc/book3s/mm: Update Oops message to print the correct translation in use
Date: Fri, 12 Jul 2019 14:25:24 +0200 [thread overview]
Message-ID: <bcd0355c-6729-3ff6-8ecc-12104d3c51cf@c-s.fr> (raw)
In-Reply-To: <87r26ve93k.fsf@concordia.ellerman.id.au>
Le 12/07/2019 à 14:22, Michael Ellerman a écrit :
> Christophe Leroy <christophe.leroy@c-s.fr> writes:
>> Le 12/07/2019 à 08:25, Michael Ellerman a écrit :
>>> "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com> writes:
> ...
>>>> diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
>>>> index 11caa0291254..b181d6860f28 100644
>>>> --- a/arch/powerpc/kernel/traps.c
>>>> +++ b/arch/powerpc/kernel/traps.c
>>>> @@ -250,15 +250,22 @@ static void oops_end(unsigned long flags, struct pt_regs *regs,
>>>> }
>>>> NOKPROBE_SYMBOL(oops_end);
>>>>
>>>> +static char *get_mmu_str(void)
>>>> +{
>>>> + if (early_radix_enabled())
>>>> + return " MMU=Radix";
>>>> + if (early_mmu_has_feature(MMU_FTR_HPTE_TABLE))
>>>> + return " MMU=Hash";
>>>> + return "";
>>>> +}
>>>
>>> We don't change MMU once we're up, so just do this logic once and stash
>>> it into a static string, rather than rechecking on every oops.
>>
>> Do we really have oops so often that we have to worry about that ?
>
> Sometimes :)
>
> But no I don't mean it's a performance issue, it just seems simpler to
> compute the value once and store it. In fact for most platforms it can
> just be a static string at compile time, it's only 64-bit Book3S that
> needs to do anything at runtime.
Right, but I'm sure GCC will take care of that since the function is
static and called only once.
Christophe
>
> cheers
>
next prev parent reply other threads:[~2019-07-12 12:36 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-07-11 14:58 [PATCH v2] powerpc/book3s/mm: Update Oops message to print the correct translation in use Aneesh Kumar K.V
2019-07-12 0:43 ` Nicholas Piggin
2019-07-12 5:31 ` Christophe Leroy
2019-07-12 6:25 ` Michael Ellerman
2019-07-12 6:48 ` Christophe Leroy
2019-07-12 12:22 ` Michael Ellerman
2019-07-12 12:25 ` Christophe Leroy [this message]
2019-11-14 9:07 ` Michael Ellerman
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