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    SubjectRe: J
    Jeremy Fitzhardinge wrote:
    > Yinghai Lu wrote:
    >> On Fri, Feb 27, 2009 at 5:51 PM, Jeremy Fitzhardinge <jeremy@goop.org>
    >> wrote:
    >>
    >>> From: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
    >>>
    >>> Rather than having special purpose init_pg_table_start/end variables
    >>> to delimit the kernel pagetable built by head_32.S, just use the brk
    >>> mechanism to extend the bss for the new pagetable.
    >>>
    >>> This patch removes init_pg_table_start/end and pg0, defines __brk_base
    >>> (which is page-aligned and immediately follows _end), initializes
    >>> the brk region to start there, and uses it for the 32-bit pagetable.
    >>>
    >> ...
    >>
    >>
    >>> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
    >>> index c246dc4..ed02176 100644
    >>> --- a/arch/x86/kernel/setup.c
    >>> +++ b/arch/x86/kernel/setup.c
    >>> @@ -113,8 +113,10 @@
    >>> #endif
    >>>
    >>> unsigned int boot_cpu_id __read_mostly;
    >>> -__initdata unsigned long _brk_start = (unsigned long)&_end;
    >>> -__initdata unsigned long _brk_end = (unsigned long)&_end;
    >>> +
    >>> +extern char __brk_base[];
    >>> +__initdata unsigned long _brk_start = (unsigned long)__brk_base;
    >>> +__initdata unsigned long _brk_end = (unsigned long)&__brk_base;
    >>>
    >>
    >> ?
    >>
    >
    > What are you asking? __brk_base is _end rounded up to a page boundary,
    > so head_32.S can use it directly for pagetable allocation. Are you
    > flagging the '&' typo? Something else?

    why start don't have &, but end has &

    YH


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