linux-kernel - Re: [microblaze-uclinux] Re: [PATCH 1/2] microblaze: add stack unwinder

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Date:	Fri, 16 Apr 2010 17:03:04 +0200
From:	Michal Simek <monstr@...str.eu>
To:	steve@...idescorp.com
CC:	Michal Simek <monstr@...str.eu>, linux-kernel@...r.kernel.org,
	microblaze-uclinux@...e.uq.edu.au
Subject: Re: [microblaze-uclinux] Re: [PATCH 1/2] microblaze: add stack unwinder

Steven J. Magnani wrote:
> On Fri, 2010-04-16 at 10:32 +0200, Michal Simek wrote:
>> Please apply this patch and do the same testing as I did.
>>
>> diff --git a/arch/microblaze/kernel/reset.c b/arch/microblaze/kernel/reset.c
>> index a1721a3..76f6587 100644
>> --- a/arch/microblaze/kernel/reset.c
>> +++ b/arch/microblaze/kernel/reset.c
>> @@ -112,8 +112,8 @@ void of_platform_reset_gpio_probe(void)
>>   void machine_restart(char *cmd)
>>   {
>>          printk(KERN_NOTICE "Machine restart...\n");
>> +       machine_shutdown();
>>          gpio_system_reset();
>> -       dump_stack();
>>          while (1)
>>                  ;
>>   }
>> @@ -121,6 +121,7 @@ void machine_restart(char *cmd)
>>   void machine_shutdown(void)
>>   {
>>          printk(KERN_NOTICE "Machine shutdown...\n");
>> +       dump_stack();
>>          while (1)
>>                  ;
>>   }
> 
> I get this:
> 
> Call Trace:
> [<20003008>] microblaze_unwind+0x68/0x94
> [<20002c24>] show_stack+0x134/0x174
> [<20002c80>] dump_stack+0x1c/0x3c
> [<20001d84>] machine_shutdown+0x30/0x40
> [<20001dc0>] machine_restart+0x2c/0x48
> [<2002a540>] kernel_restart+0x5c/0x80
> [<2002a6b8>] sys_reboot+0x11c/0x218
> SYSCALL
> [<2d5c0248>] PID 118 [reboot]
> 
> Is your problem on a MMU or noMMU system?

Interesting. It was noMMU system.

> 
> If the unwinder stops early, it found a return address outside the
> kernel text, or couldn't find the addik that creates a stack frame - but
> there's not enough information here to tell what happened. In your case
> the backtrace goes off the rails before getting to the frame for
> dump_stack(), which is where the stack dump begins. We'd need to see the
> 21 words preceding the dump (show_stack's frame is 13 words, and
> microblaze_unwind's is 8) to know why.
> 
> Can you uncomment the #define DEBUG in unwind.c and try it again?

will do next week and let you know.

Thanks,
Michal


> 
> Thanks,
> ------------------------------------------------------------------------
>  Steven J. Magnani               "I claim this network for MARS!
>  www.digidescorp.com              Earthling, return my space modulator!"
> 
>  #include <standard.disclaimer>
> 
> 
> --
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-- 
Michal Simek, Ing. (M.Eng)
w: www.monstr.eu p: +42-0-721842854
Maintainer of Linux kernel 2.6 Microblaze Linux - http://www.monstr.eu/fdt/
Microblaze U-BOOT custodian
--
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