how do I increase default kernel stack size for my MPC8548 board?

how do I increase default kernel stack size for my MPC8548 board?

[hank peng]

In kernel source, default kernel stack size for PPC32 is as follows:
#if defined(CONFIG_PPC64)
#define THREAD_SHIFT		14
#elif defined(CONFIG_PPC_256K_PAGES)
#define THREAD_SHIFT		15
#else
#define THREAD_SHIFT		13
#endif

#define THREAD_SIZE		(1 << THREAD_SHIFT)

So, default value is 8K, but now I want to increase it to 16K, is it
OK just to change THREAD_SHIFT to 14? or is there some patch needed?

-- 
The simplest is not all best but the best is surely the simplest!

Re: how do I increase default kernel stack size for my MPC8548 board?

[perth1415]

Hi,

I have the exact same query. We have a board with MPC8378, which is a 32-bit
processor running 2.6-25 kernel. I increased THREAD_SHIFT to 14. Now the
board hangs just after the "Uncompressing Kernel Image ... OK" message from
U-boot.
Is there any other change required for 16k stack apart from THREAD_SHIFT?

Thanks,
Partha



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Re: how do I increase default kernel stack size for my MPC8548 board?

[perth1415]

Looks like I found the issue :-) The stack size for init task needs to be
updated too. Right now it's by default set to 8K for PPC32.

In arch/powerpc/kernel/vmlinux.lds.S -
===
    /* The initial task and kernel stack */
#ifdef CONFIG_PPC32
    . = ALIGN(8192);
#else
    . = ALIGN(16384);
#endif
===

Problem is, how do we link this to THREAD_SHIFT?

Thanks,
Partha



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Re: how do I increase default kernel stack size for my MPC8548 board?

[Scott Wood]

On Tue, 2014-03-11 at 07:19 -0700, perth1415 wrote:
> Looks like I found the issue :-) The stack size for init task needs to be
> updated too. Right now it's by default set to 8K for PPC32.
> 
> In arch/powerpc/kernel/vmlinux.lds.S -
> ===
>     /* The initial task and kernel stack */
> #ifdef CONFIG_PPC32
>     . = ALIGN(8192);
> #else
>     . = ALIGN(16384);
> #endif
> ===
> 
> Problem is, how do we link this to THREAD_SHIFT?

Have you tried:

	. = ALIGN(THREAD_SIZE)

?

Or just use a newer kernel, where this is already done. :-)

-Scott