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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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