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

Submitted by Albert Herranz on Dec. 3, 2009, 8:34 p.m.

Details

Message ID 731eb73d0a309d0c23b30bea3718b976c3782b71.1259871725.git.albert_herranz@yahoo.es
State Superseded
Headers show

Commit Message

Albert Herranz Dec. 3, 2009, 8:34 p.m.
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@yahoo.es>
---
 arch/powerpc/include/asm/fixmap.h |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

Comments

Benjamin Herrenschmidt Dec. 11, 2009, 10:15 p.m.
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@yahoo.es>

Acked-by: Benjamin Herrenschmidt <benh@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,

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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,