Re: [uClinux-dev] bootmem - which way ?

From: Ilan Pollak (ilanp@galileo.co.il)
Date: Tue Jul 23 2002 - 04:25:51 EDT


Hi David and thanks for the help!

David McCullough wrote:

>Jivin Ilan Pollak lays it down ...
>
>>Hi all,
>>Can someone please explain this part of the function 'setup_arch' from 
>>linux-2.4.x/arch/armnommu/kernel/setup.c ?
>>
>
>
>Which ARM target are you building for.  That will help with which settings
>are causing it to fail.
>
I'm building for AT91 which is an ARM7TDMI, on an EB40LS board

>>#if 1
>>    bootmem_init(&meminfo);
>>#else
>>    bootmap_size= init_bootmem_node(
>>              NODE_DATA(0),
>>              memory_start >> PAGE_SHIFT,
>>              PAGE_OFFSET >> PAGE_SHIFT,
>>              END_MEM >> PAGE_SHIFT);
>> 
>>    free_bootmem(memory_start, END_MEM - memory_start);
>>    reserve_bootmem(memory_start, bootmap_size);
>>#endif
>>
>>if I change to #if 0 - the lower part work, and everything is cool ! 
>>(until my former email...)
>>the problem is , that the distribution (20020701), comes with the #if 1 
>>checked, then i get Kernel Bug in bootmem.c::reserve_bootmem_core, the 
>>starting index is bigger the ending one.
>>and the next line is a BUG also.
>>Can someone please tell me what's the difference ?
>>thanks,
>>
>
>I think the key here will be the value of PHYS_OFFSET.  I suspect it will
>need to be page aligned at least.
>
>Obviously some of the platforms are working and some aren't.  Look at
>DRAM_BASE and DRAM_SIZE (MEM_END) and also at PHYS_OFFSET to see the
>differences.
>
checked those too, they seem fine to me:
DRAM_BASE = 0x02000000;
DRAM_SIZE = 0x00200000;
PHYS_OFFSET (== PAGE_OFFSET) = 0x02000000

but then again, something must go wrong there ...
What's the price of choosing the other path (the '#if 0' way) ?
thanks,
ilan

>
>I believe there was something posted to the list on thsi topic quite a
>while back which resulted in the patch from "if 0" to "if 1".  You might
>be able to find a few more details tehre,
>
>Cheers,
>Davidm
>
sorry, couldn't find it, any link?

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