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SubjectRe: [PATCH 5/6] early_res: seperate common memmap func from e820.c to fw_memmap.c
On 03/10/2010 01:50 PM, Russell King wrote:
> On Wed, Mar 10, 2010 at 01:24:26PM -0800, Yinghai Lu wrote:
>> +/* How much should we pad RAM ending depending on where it is? */
>> +static unsigned long __init ram_alignment(resource_size_t pos)
>> +{
>> + unsigned long mb = pos >> 20;
>> +
>> + /* To 64kB in the first megabyte */
>> + if (!mb)
>> + return 64*1024;
>> +
>> + /* To 1MB in the first 16MB */
>> + if (mb < 16)
>> + return 1024*1024;
>> +
>> + /* To 64MB for anything above that */
>> + return 64*1024*1024;
>> +}
>
> This doesn't make sense for generic code.
>
> 1. All architectures do not have RAM starting at physical address 0.
> 2. What about architectures which have relatively little memory (maybe
> 16MB total) split into four chunks of 4MB spaced at 512MB ?

>
> Other comments:
>
> 1. It doesn't support mem=size@base, which is used extensively on ARM.

current x86, need to use exactmap...
so could add sth in arch/arm/setup.c to set it.


> 2. How does memory get allocated for creating things like page tables?
find_fw_memmap_area
rerserve_early

>
> Currently, bootmem supports ARM very well with support for flatmem,
> sparsemem and discontigmem models (the latter being deprecated). Can
> this code support all three models?
should be ok.
>
> Where are patches 1 to 4?

my bad, it still have 1/4, 2/4, 3/4, 4/4

>
> Lastly, why exactly is bootmem being eliminated? Bootmem offers more
> flexible functionality than this e820 code appears at first read-through
> seems to.
less layer before slab...

fw_memmap.c could be simplified by keeping more stuff in arch/x86/kernel/e820.c
will have one fw_mem_internal.h and only be included by fw_memmap.c and arch fw_memmap.c.

YH





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