Re: [PATCH] x86-32: use brk segment for allocating initial kernel pagetable

[Yinghai Lu <yinghai@kernel.org>]

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;

?

YH