Help! mpc8247 porting kernel 2.6.25 problem.

Help! mpc8247 porting kernel 2.6.25 problem.

[张世乐]

Hi All,

I encounter a problem when porting kernel 2.6.25 to a mpc8247 platform board.

after run command line: bootm 300000 - 600000
the output of u-boot like this:

[snip]

Uncompressing Kernel Image ... OK
Booting using the fdt at 0x600000

[nothing output and hanging here]

I use the led on the board to trace the kernel fund it stop in the function

setup_common_caches  in arch/powerpc/kernel/cpu_setup_6xx.S

Can you give me some ideas?

Thanks!

Re: Help! mpc8247 porting kernel 2.6.25 problem.

[Scott Wood]

On Mon, Apr 21, 2008 at 11:06:28AM +0800, 张世乐 wrote:
> Uncompressing Kernel Image ... OK
> Booting using the fdt at 0x600000
> 
> [nothing output and hanging here]
> 
> I use the led on the board to trace the kernel fund it stop in the function
> 
> setup_common_caches  in arch/powerpc/kernel/cpu_setup_6xx.S
> 
> Can you give me some ideas?

That's probably not where it's actually stopping, but rather where caches
are enabled without the MMU, thus making it difficult to access devices. 
You can try placing a dcbf after each write to the LED register, though
this may perturb nearby registers.

Have you tried enabling early debug printk?

-Scott

Re: Help! mpc8247 porting kernel 2.6.25 problem.

[张世乐]

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Re: Help! mpc8247 porting kernel 2.6.25 problem.

[Scott Wood]

On Tue, Apr 22, 2008 at 01:10:54PM +0800, 张世乐 wrote:
> Thank you, Doctor Scott. I'm very grateful to you for you kindly help.
> 
> I'll try the way you suggested soon.
> 
> And, my code for light the led run as follows:
> 
> void set_led_a_red(void)
> {
> 	/*PDIRC: 0xfc010d40*/
> 	/*PPARC: 0xfc010d44*/
> 	/*PODRC: 0xfc010d4c*/
> 	/*PDATC: 0xfc010d50*/
> 	*((unsigned long *)(0xfb010d40)) |= 0x000000d4;
> 	*((unsigned long *)(0xfb010d44)) &= ~0x000000d4;
> 	*((unsigned long *)(0xfb010d4c)) &= ~0x000000d4;
> 	*((unsigned long *)(0xfb010d50)) |= 0x00000004;
> 	*((unsigned long *)(0xfb010d50)) &= ~0x00000010;
> }

Use out_be32(), and put a dcbf at the end.  If the dcbf doesn't help, try
not accessing any I/O until after the MMU is set up, and use a
cache-inhibited BAT mapping.  It's usually not between enabling caches
and enabling the MMU that something goes wrong, but it is a rather
annoying debug barrier.

As for early debug output not working, another possibility besides the
descriptor address is that ppc_md.probe is failing, or that your board
file doesn't set ppc_md.progress to udbg_progress.

-Scott