Re: [PATCH v2] powerpc: Fix xmon for systems without MSR[RI]

[Jimi Xenidis <jimix@pobox.com>]

On Sep 23, 2011, at 11:32 AM, Scott Wood wrote:

> On 09/23/2011 10:01 AM, Jimi Xenidis wrote:
>> From: David Gibson <dwg@au1.ibm.com>
>>=20
>> Based on patch by David Gibson <dwg@au1.ibm.com>
>>=20
>> xmon has a longstanding bug on systems which are SMP-capable but lack
>> the MSR[RI] bit.  In these cases, xmon invoked by IPI on secondary
>> CPUs will not properly keep quiet, but will print stuff, thereby
>> garbling the primary xmon's output.  This patch fixes it, by ignoring
>> the RI bit if the processor does not support it.
>>=20
>> There's already a version of this for 4xx upstream, which we'll need
>> to extend to other RI-lacking CPUs at some point.  For now this adds
>> Book3e processors to the mix.
>>=20
>> Signed-off-by: Jimi Xenidis <jimix@pobox.com>
>>=20
>> ---
>> Restricted it to Book3e
>> ---
>> arch/powerpc/xmon/xmon.c |    4 ++--
>> 1 files changed, 2 insertions(+), 2 deletions(-)
>>=20
>> diff --git a/arch/powerpc/xmon/xmon.c b/arch/powerpc/xmon/xmon.c
>> index 42541bb..13f82f8 100644
>> --- a/arch/powerpc/xmon/xmon.c
>> +++ b/arch/powerpc/xmon/xmon.c
>> @@ -340,8 +340,8 @@ int cpus_are_in_xmon(void)
>>=20
>> static inline int unrecoverable_excp(struct pt_regs *regs)
>> {
>> -#ifdef CONFIG_4xx
>> -	/* We have no MSR_RI bit on 4xx, so we simply return false */
>> +#if defined(CONFIG_4xx) || defined(CONFIG_BOOK3E)
>> +	/* We have no MSR_RI bit on 4xx or Book3e, so we simply return =
false */
>> 	return 0;
>> #else
>> 	return ((regs->msr & MSR_RI) =3D=3D 0);
>=20
> How is CONFIG_BOOK3E better than CONFIG_BOOKE?  Both e500mc (has RI) =
and
> e500v2 (doesn't have RI) will select both symbols.  Sounds like it
> should be a cputable flag.

Ben was not in favor of wasting a cpu feature bit on this.
I figured that since Book3e ISA does not support an RI bit than I would =
leave that too the those who extend it. :)
Any other ideas are welcome.

-JX


>=20
> -Scott
>=20