J

[Jeremy Fitzhardinge]

Yinghai Lu wrote:
> On Fri, Feb 27, 2009 at 5:51 PM, Jeremy Fitzhardinge <jeremy@xxxxxxxx> wrote:
>   
> > From: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
> >
> > 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?

   J
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