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Date: Thu, 11 Nov 2010 06:26:33 -0600
From: Kumar Gala <galak@...nel.crashing.org>
To: Xie Shaohui-B21989 <B21989@...escale.com>
Cc: "Bounine, Alexandre" <Alexandre.Bounine@....com>,
<akpm@...ux-foundation.org>, <linux-kernel@...r.kernel.org>,
<linuxppc-dev@...ts.ozlabs.org>,
Li Yang-R58472 <R58472@...escale.com>,
Gala Kumar-B11780 <B11780@...escale.com>,
Zang Roy-R61911 <R61911@...escale.com>
Subject: Re: [PATCH 3/4][v2] fsl_rio: move machine_check handler into machine_check_e500 & machine_check_e500mc
On Nov 11, 2010, at 4:19 AM, Xie Shaohui-B21989 wrote:
>
>
>
> Best Regards,
> Shaohui Xie
>
>
>> -----Original Message-----
>> From: Bounine, Alexandre [mailto:Alexandre.Bounine@....com]
>> Sent: Thursday, November 11, 2010 6:55 AM
>> To: Xie Shaohui-B21989; akpm@...ux-foundation.org
>> Cc: linux-kernel@...r.kernel.org; linuxppc-dev@...ts.ozlabs.org; Li
> Yang-
>> R58472; Gala Kumar-B11780; Zang Roy-R61911
>> Subject: RE: [PATCH 3/4][v2] fsl_rio: move machine_check handler into
>> machine_check_e500 & machine_check_e500mc
>>
>> Shaohui Xie <b21989@...escale.com> wrote:
>>>
>>> diff --git a/arch/powerpc/kernel/traps.c
> b/arch/powerpc/kernel/traps.c
>>> index a45a63c..2a5fb9d 100644
>>> --- a/arch/powerpc/kernel/traps.c
>>> +++ b/arch/powerpc/kernel/traps.c
>>> @@ -55,6 +55,7 @@
>>> #endif
>>> #include <asm/kexec.h>
>>> #include <asm/ppc-opcode.h>
>>> +#include <linux/rio.h>
>>>
>>> #if defined(CONFIG_DEBUGGER) || defined(CONFIG_KEXEC) int
>>> (*__debugger)(struct pt_regs *regs) __read_mostly; @@ -500,6 +501,13
>>> @@ int machine_check_e500mc(struct pt_regs *regs)
>>> reason & MCSR_MEA ? "Effective" : "Physical",
>> addr);
>>> }
>>>
>>> + if (reason & MCSR_BUS_RBERR) {
>>> + printk("Bus - Read Data Bus Error\n"); #ifdef
> CONFIG_RAPIDIO
>>> + recoverable = fsl_rio_mcheck_exception(regs); #endif
>>> + }
>>> +
>>> mtspr(SPRN_MCSR, mcsr);
>>> return mfspr(SPRN_MCSR) == 0 && recoverable; } @@ -527,8
> +535,12
>> @@
>>> int machine_check_e500(struct pt_regs *regs)
>>> printk("Bus - Write Address Error\n");
>>> if (reason & MCSR_BUS_IBERR)
>>> printk("Bus - Instruction Data Error\n");
>>> - if (reason & MCSR_BUS_RBERR)
>>> + if (reason & MCSR_BUS_RBERR) {
>>> printk("Bus - Read Data Bus Error\n");
>>> +#ifdef CONFIG_RAPIDIO
>>> + fsl_rio_mcheck_exception(regs);
>>> +#endif
>>> + }
>>> if (reason & MCSR_BUS_WBERR)
>>> printk("Bus - Read Data Bus Error\n");
>>> if (reason & MCSR_BUS_IPERR)
>>
>> This implementation breaks an intended use of
>> fsl_rio_mcheck_exception():
>> 1. for e500 it does not check the return value of the rio handler and
>> crashes the system even after RIO Mchk was serviced. Looks like e500mc
>> version handles it better but I have no HW to test it.
>> 2. the RIO Mchk is expected to be handled quietly but here it has many
>> printk's. May be it is better to call the fsl_rio_mcheck_exception()
>> handler in very beginning and simply exit if it returns 1.
>>
>> Alex.
> [Xie Shaohui-B21989] Hi Alex, seems your suggestion is some kind of
> conflict with Kumar, you can have a look at
> http://patchwork.ozlabs.org/patch/67774/
I think Alex's comment is the fact we ignore the 'return' value in the machine_check_e500 case.
- k--
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