405GPr support in linux2.4.18

405GPr support in linux2.4.18

[Laurent Mohin]

Hello all,

I'm designing a board with 405GP processor. I'm now trying to have it
working with a 405GPr version.
I've started to configure it working in legacy mode and made the necessary
changes in PPCBoot.

Once downloaded, my kernel hung in early_init function when it called the
memset_io to zero the BSS. Using a BDI2000 debugger, I saw that I've
reached the bad_page_fault function.

The only difference I know between 405GP and 405GPr in legacy mode is data
cache size. How does the kernel manage it?

I'm currently using kernel 2.4.18 from Montavista.

Any help is welcome,

Laurent


Laurent MOHIN
ACTERNA


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Re: 405GPr support in linux2.4.18

[Eugene Surovegin]

At 02:11 AM 2/18/2003, Laurent Mohin wrote:
>I'm designing a board with 405GP processor. I'm now trying to have it
>working with a 405GPr version.
>I've started to configure it working in legacy mode and made the necessary
>changes in PPCBoot.
>
>Once downloaded, my kernel hung in early_init function when it called the
>memset_io to zero the BSS. Using a BDI2000 debugger, I saw that I've
>reached the bad_page_fault function.
>
>The only difference I know between 405GP and 405GPr in legacy mode is data
>cache size. How does the kernel manage it?

We successfully run 405GPr based board (in legacy mode) with the _same_
kernel we used for 405GP.
We don't use any 405GPr specific features though.

As far as I understand, the only function which depends on the data cache
size is flush_dcache_all in (arch/ppc/kernel/misc.S).
But it already handles the worst case which is 440GP (32K), so no change is
needed for 405GPr.

Eugene


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Re: 405GPr support in linux2.4.18

[Eugene Surovegin]

At 12:54 AM 2/19/2003, Eugene Surovegin wrote:

>At 02:11 AM 2/18/2003, Laurent Mohin wrote:
>>I'm designing a board with 405GP processor. I'm now trying to have it
>>working with a 405GPr version.
>>I've started to configure it working in legacy mode and made the necessary
>>changes in PPCBoot.
>>
>>Once downloaded, my kernel hung in early_init function when it called the
>>memset_io to zero the BSS. Using a BDI2000 debugger, I saw that I've
>>reached the bad_page_fault function.
>>
>>The only difference I know between 405GP and 405GPr in legacy mode is data
>>cache size. How does the kernel manage it?
>
>We successfully run 405GPr based board (in legacy mode) with the _same_
>kernel we used for 405GP.
>We don't use any 405GPr specific features though.
>
>As far as I understand, the only function which depends on the data cache
>size is flush_dcache_all in (arch/ppc/kernel/misc.S).
>But it already handles the worst case which is 440GP (32K), so no change is
>needed for 405GPr.

Small correction. We use 2_4_devel tree.

I just checked MVL 2.1 and 3.0 sources.
flush_dcache_all in those trees is an old one, which doesn't support caches
large than 8K.

You may consider using 2_4_devel for your 405GPr based board.

Eugene


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Re: 405GPr support in linux2.4.18

[Laurent Mohin]

Eugene,

Thanks for your response.

I've checked that when my kernel hangs, it hasn't hit the flush_dcache_all
breakpoint I've put.
Nevertheless, I will try using the new function used in the 2_4_devel tree.

Laurent


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