[PATCH] makedumpfile: ppc64: Auto-detect the correct MAX_PHYSMEM_BITS used in vmcore being analyzed.

[Atsushi Kumagai]

Hello Mahesh,

On Tue, 29 Jan 2013 11:19:01 +0530
Mahesh J Salgaonkar <mahesh at linux.vnet.ibm.com> wrote:

> From: Mahesh Salgaonkar <mahesh at linux.vnet.ibm.com>
> 
> The latest upstream kernel commit 048ee0993ec8360abb0b51bdf8f8721e9ed62ec4 adds
> 64TB support to ppc64 kernel and bumps the MAX_PHYSMEM_BITS from 44 to 46. This
> change causes sparsemem extreme check to fail in makedumpfile.
> 
> This patch auto-detects the correct value to use for MAX_PHYSMEM_BITS by
> examining the mem_section array size from the vmcore being analyzed.
> 
> This patch has been tested on upstream kernel 3.8.0-rc4 and older kernel
> 2.6.32.

Thanks for your work, I'll merge this patch into the next version.


Thanks
Atsushi Kumagai

> Reported-by: Dave Anderson <anderson at redhat.com>
> Reported-by: Dave Young <dyoung at redhat.com>
> Signed-off-by: Mahesh Salgaonkar <mahesh at linux.vnet.ibm.com>
> ---
>  arch/ppc64.c   |   27 ++++++++++++++++++++++++++-
>  makedumpfile.h |    3 ++-
>  2 files changed, 28 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/ppc64.c b/arch/ppc64.c
> index 1cb69e1..afbaf55 100644
> --- a/arch/ppc64.c
> +++ b/arch/ppc64.c
> @@ -25,12 +25,37 @@
>  #include "../makedumpfile.h"
>  
>  int
> +set_ppc64_max_physmem_bits(void)
> +{
> +	long array_len = ARRAY_LENGTH(mem_section);
> +	/*
> +	 * The older ppc64 kernels uses _MAX_PHYSMEM_BITS as 42 and the
> +	 * newer kernels 3.7 onwards uses 46 bits.
> +	 */
> +
> +	info->max_physmem_bits  = _MAX_PHYSMEM_BITS_ORIG ;
> +	if ((array_len == (NR_MEM_SECTIONS() / _SECTIONS_PER_ROOT_EXTREME()))
> +		|| (array_len == (NR_MEM_SECTIONS() / _SECTIONS_PER_ROOT())))
> +		return TRUE;
> +
> +	info->max_physmem_bits  = _MAX_PHYSMEM_BITS_3_7;
> +	if ((array_len == (NR_MEM_SECTIONS() / _SECTIONS_PER_ROOT_EXTREME()))
> +		|| (array_len == (NR_MEM_SECTIONS() / _SECTIONS_PER_ROOT())))
> +		return TRUE;
> +
> +	return FALSE;
> +}
> +
> +int
>  get_machdep_info_ppc64(void)
>  {
>  	unsigned long vmlist, vmalloc_start;
>  
>  	info->section_size_bits = _SECTION_SIZE_BITS;
> -	info->max_physmem_bits  = _MAX_PHYSMEM_BITS;
> +	if (!set_ppc64_max_physmem_bits()) {
> +		ERRMSG("Can't detect max_physmem_bits.\n");
> +		return FALSE;
> +	}
>  	info->page_offset = __PAGE_OFFSET;
>  
>  	if (SYMBOL(_stext) == NOT_FOUND_SYMBOL) {
> diff --git a/makedumpfile.h b/makedumpfile.h
> index d2bdc0c..d758a3c 100644
> --- a/makedumpfile.h
> +++ b/makedumpfile.h
> @@ -566,7 +566,8 @@ do { \
>  #define VMALLOCBASE     	(0xD000000000000000)
>  #define KVBASE			(SYMBOL(_stext))
>  #define _SECTION_SIZE_BITS	(24)
> -#define _MAX_PHYSMEM_BITS	(44)
> +#define _MAX_PHYSMEM_BITS_ORIG  (44)
> +#define _MAX_PHYSMEM_BITS_3_7   (46)
>  #endif
>  
>  #ifdef __powerpc32__
>