linux-kernel - Re: [v2][PATCH 4/7] book3e/kexec/kdump: introduce a kexec kernel flag

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Message-ID: <51DBC118.6030100@windriver.com>
Date:	Tue, 9 Jul 2013 15:51:52 +0800
From:	"tiejun.chen" <tiejun.chen@...driver.com>
To:	Bhushan Bharat-R65777 <R65777@...escale.com>
CC:	"benh@...nel.crashing.org" <benh@...nel.crashing.org>,
	"linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [v2][PATCH 4/7] book3e/kexec/kdump: introduce a kexec kernel
 flag

On 07/02/2013 01:37 PM, Bhushan Bharat-R65777 wrote:
>
>
>> -----Original Message-----
>> From: Linuxppc-dev [mailto:linuxppc-dev-
>> bounces+bharat.bhushan=freescale.com@...ts.ozlabs.org] On Behalf Of Tiejun Chen
>> Sent: Thursday, June 20, 2013 1:23 PM
>> To: benh@...nel.crashing.org
>> Cc: linuxppc-dev@...ts.ozlabs.org; linux-kernel@...r.kernel.org
>> Subject: [v2][PATCH 4/7] book3e/kexec/kdump: introduce a kexec kernel flag
>>
>> We need to introduce a flag to indicate we're already running
>> a kexec kernel then we can go proper path. For example, We
>> shouldn't access spin_table from the bootloader to up any secondary
>> cpu for kexec kernel, and kexec kernel already know how to jump to
>> generic_secondary_smp_init.
>>
>> Signed-off-by: Tiejun Chen <tiejun.chen@...driver.com>
>> ---

[snip]

>> +++ b/arch/powerpc/platforms/85xx/smp.c
>> @@ -150,6 +150,9 @@ static int __cpuinit smp_85xx_kick_cpu(int nr)
>>   	int hw_cpu = get_hard_smp_processor_id(nr);
>>   	int ioremappable;
>>   	int ret = 0;
>> +#if defined(CONFIG_KEXEC) || defined(CONFIG_CRASH_DUMP)
>> +	unsigned long *ptr;
>> +#endif
>
> What about if we can remove the ifdef around *ptr ...
>
>>
>>   	WARN_ON(nr < 0 || nr >= NR_CPUS);
>>   	WARN_ON(hw_cpu < 0 || hw_cpu >= NR_CPUS);
>> @@ -238,11 +241,22 @@ out:
>>   #else
>>   	smp_generic_kick_cpu(nr);
>>
>> +#if defined(CONFIG_KEXEC) || defined(CONFIG_CRASH_DUMP)
>> +	ptr  = (unsigned long *)((unsigned long)&__run_at_kexec);
>
> ... #endif here ...
>
>> +	/* We shouldn't access spin_table from the bootloader to up any
>> +	 * secondary cpu for kexec kernel, and kexec kernel already
>> +	 * know how to jump to generic_secondary_smp_init.
>> +	 */
>> +	if (!*ptr) {
>> +#endif
>
> ... remove #endif ...
>
>>   	flush_spin_table(spin_table);
>>   	out_be32(&spin_table->pir, hw_cpu);
>>   	out_be64((u64 *)(&spin_table->addr_h),
>>   	  __pa((u64)*((unsigned long long *)generic_secondary_smp_init)));
>>   	flush_spin_table(spin_table);
>> +#if defined(CONFIG_KEXEC) || defined(CONFIG_CRASH_DUMP)
>> +	}
>> +#endif
>
> --- remove above 3 lines

I'd like to try to address your comments next version.

Thanks

Tiejun
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