Re: [Crash-utility] [PATCH] crash: s390x: Auto-detect the correct MAX_PHYSMEM_BITS used in vmcore being analyzed

Hello Dave and Mahesh, We also tried to solve the problem and came up with an alternative solution. The function s390x_max_physmem_bits() solves the following equation: array_len == NR_MEM_SECTIONS / SECTIONS_PER_ROOT 2^(MAX_PYSMEM_BITS - SECTION_SIZE_BITS) --------------------------------------- == PAGE_SIZE ------------------------- sizeof(struct mem_section) This leads to the following: MAX_PYSMEM_BITS == SECTION_SIZE_BITS + log2(array_len) + log2(PAGE_SIZE) - log2(sizeof(struct mem_section)); I tested the patch with 42 and 46 bits and for both it seems to work. I will leave now for vacation and will return January the 9th 2012. I leave it to you which solution to take.

Merry Christmas! Michael PS: I think this patch also fixes a bug in verify_ptn()... BTOP vs. PTOB :-)

--- kernel.c | 2 +- memory.c | 2 +- s390x.c | 17 ++++++++++++++++- 3 files changed, 18 insertions(+), 3 deletions(-) --- a/kernel.c +++ b/kernel.c @@ -275,7 +275,7 @@ kernel_init() MEMBER_OFFSET_INIT(prio_array_nr_active, "prio_array", "nr_active"); STRUCT_SIZE_INIT(runqueue, rqstruct); STRUCT_SIZE_INIT(prio_array, "prio_array"); - + STRUCT_SIZE_INIT(mem_section, "mem_section"); MEMBER_OFFSET_INIT(rq_cfs, "rq", "cfs"); /* --- a/memory.c +++ b/memory.c @@ -13601,7 +13601,7 @@ verify_pfn(ulong pfn) for (i = machdep->max_physmem_bits; i < machdep->bits; i++) mask |= ((physaddr_t)1 << i); - if (mask & BTOP(pfn)) + if (mask & PTOB(pfn)) return FALSE; return TRUE; --- a/s390x.c +++ b/s390x.c @@ -17,6 +17,7 @@ */ #ifdef S390X #include <elf.h> +#include <math.h> #include "defs.h" #include "netdump.h" @@ -283,6 +284,19 @@ static void s390x_process_elf_notes(void } /* + * The older s390x kernels use _MAX_PHYSMEM_BITS as 42 and the + * newer kernels use 46 bits. This function calculates the bits + * via a generic function. + */ +static int s390x_max_physmem_bits(void) +{ + unsigned long array_len = get_array_length("mem_section", NULL, 0); + + return _SECTION_SIZE_BITS + log2(array_len) + 12 /* log2(PAGE_SIZE) */ + - log2(SIZE(mem_section)); +} + +/* * Do all necessary machine-specific setup here. This is called several * times during initialization. */ @@ -350,13 +364,14 @@ s390x_init(int when) if (!machdep->hz) machdep->hz = HZ; machdep->section_size_bits = _SECTION_SIZE_BITS; - machdep->max_physmem_bits = _MAX_PHYSMEM_BITS; + machdep->max_physmem_bits = s390x_max_physmem_bits(); s390x_offsets_init(); break; case POST_INIT: break; } + fprintf(stderr, "XXX %d\n", machdep->max_physmem_bits); } /*