[RFC PATCH v4 1/2] powerpc: reserve fixmap entries for early debug

[Benjamin Herrenschmidt]

On Thu, 2009-12-03 at 21:34 +0100, Albert Herranz wrote:
> Add a set of entries to the fixmap table to allow usage of known
> reserved virtual address space by early debug code.
> 
> The address space reserved is the top 128K of the 32-bit address
> space. This allows, if required, the use of a BAT to do the mappings.
> 
> Signed-off-by: Albert Herranz <albert_herranz at yahoo.es>

Acked-by: Benjamin Herrenschmidt <benh at kernel.crashing.org>

That will do for now. I have ideas to clean it up a bit but for now it's
fine.

> ---
>  arch/powerpc/include/asm/fixmap.h |    3 +++
>  1 files changed, 3 insertions(+), 0 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/fixmap.h b/arch/powerpc/include/asm/fixmap.h
> index f1f4e23..5c2c023 100644
> --- a/arch/powerpc/include/asm/fixmap.h
> +++ b/arch/powerpc/include/asm/fixmap.h
> @@ -44,6 +44,9 @@
>   */
>  enum fixed_addresses {
>  	FIX_HOLE,
> +	/* reserve the top 128K for early debugging purposes */
> +	FIX_EARLY_DEBUG_TOP = FIX_HOLE,
> +	FIX_EARLY_DEBUG_BASE = FIX_EARLY_DEBUG_TOP+((128*1024)/PAGE_SIZE)-1,
>  #ifdef CONFIG_HIGHMEM
>  	FIX_KMAP_BEGIN,	/* reserved pte's for temporary kernel mappings */
>  	FIX_KMAP_END = FIX_KMAP_BEGIN+(KM_TYPE_NR*NR_CPUS)-1,