Bootmem broke ARM

From: Russell King (rmk+lkml_at_arm.linux.org.uk)
Date: 11/16/03

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    Date:	Sun, 16 Nov 2003 10:15:35 +0000
    To: Linux Kernel List <linux-kernel@vger.kernel.org>, Andrew Morton <akpm@osdl.org>, Linus Torvalds <torvalds@osdl.org>
    
    

    Andrew & others,

    2.6 contains a change to init_bootmem_core() which now sorts the nodes
    according to their start pfn. This change occurred in revision 1.20 of
    bootmem.c. Unfortunately, this active sorting broke ARM discontig memory
    support.

    With previous kernels, the nodes are added to the list in reverse order,
    so architecture code knew we had to add the highest PFN first and the
    lowest PFN node last.

    However, we now sort the nodes using node_start_pfn, which, at this point,
    will be uninitialised - the responsibility for initialising this field
    is with the generic code - in free_area_init_node() which occurs well
    after bootmem has been initialised.

    The result of this change is that we now add nodes to the tail of the
    pgdat list, which is the opposite way to 2.4.

    This causes problems for ARM because we need to use bootmem to initialise
    the kernels page tables, and we can only allocate these from node 0 - none
    of the other nodes are mapped into memory at this point.

    I, therefore, believe this change is bogus. Can it be reverted please?

    -- 
    Russell King
     Linux kernel    2.6 ARM Linux   - http://www.arm.linux.org.uk/
     maintainer of:  2.6 PCMCIA      - http://pcmcia.arm.linux.org.uk/
                     2.6 Serial core
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