Now I set _SECTION_SIZE_BITS 22 and see what happens next. I found that readmem for "page table" failed while excuting init_unwind_tables() in unwind_arm.c and crash exited. crash: invalid kernel virtual address: f67f000 type: "page table" Instead of investigating this issue, I continue by skipping init_unwind_tables for a while. Because crash gives me a prompt now and I am quite interested in whether it gives me some useful information or not. Takuo >Thanks Dave, MW, Jan, > >I tried the patch which set machdep->section_size_bits and machdep->max_physmem_bits. > >When _SECTION_SIZE_BITS is 28, I got the following error, and failed in sparse_mem_init() >PAGESIZE=4096 >mem_section_size = 0 >NR_SECTION_ROOTS = 0 >NR_MEM_SECTIONS = 16 >SECTIONS_PER_ROOT = 512 >SECTION_ROOT_MASK = 0x1ff >PAGES_PER_SECTION = 65536 >crash: invalid size request: 0 type: "memory section root table" > > >And when _SECTION_SIZE_BITS is 22, I got the following and sparse_mem_init() returns with out error. > >PAGESIZE=4096 >mem_section_size = 8 >NR_SECTION_ROOTS = 2 >NR_MEM_SECTIONS = 1024 >SECTIONS_PER_ROOT = 512 >SECTION_ROOT_MASK = 0x1ff >PAGES_PER_SECTION = 1024 > > > >In memory.c:sparse_mem_init(), > vt->mem_sec is malloced as mem_section_size bytes block and readmem is called. >I suppose the mem_section_size should not be zero. I do not know _SECTION_SIZE_BITS 22 is correct or not, >but the following caliculation of NR_SECTION_ROOTS() looks suspicious to me. >#define NR_SECTION_ROOTS() (NR_MEM_SECTIONS() / SECTIONS_PER_ROOT()) > >Something like (((NR_MEM_SECTIONS() - 1)/ SECTIONS_PER_ROOT()) + 1) ? > > >Best Regard, > >Takuo > > > >>[ dropped my Nokia address from the CC list, since I'm not working for Nokia >> anymore ] >> >>On Tue, May 24, 2011 at 09:58:48AM -0400, Dave Anderson wrote: >>> >>> BTW, I await any patches from the ARM folks to set these bits >>> appropriately. Currently there is this for ARM in defs.h: >>> >>> #ifdef ARM >>> ... [ cut ] ... >>> >>> #define _SECTION_SIZE_BITS 28 >>> #define _MAX_PHYSMEM_BITS 32 >>> >>> #endif /* ARM */ >>> >>> Yet you state above that you're using 22 for _SECTION_SIZE_BITS. >> >>This varies between different SoCs and it is not used by others. Since it is >>not stored in a crashdump IIRC, we really cannot set that value dynamically. >> >>So I see two options: >> >> 1) leave it as is and make crash to complain when it detects such >> situation or >> 2) guess the values and try to do the right thing (TM) >> >>My preference goes with 2) provided that we can get it working on majority of >>the ARM SoCs. >> >>We could try to stick with _SECTION_SIZE_BITS=28, as it seems to be largest >>currently used section size amongst different ARM SoCs, and hope that it works >>with others where this is smaller. >> >>Jan, Takuo: maybe you could try whether following patch works? I don't have >>any hardware which use SPARSEMEM so I'm unable to test it. >> >>Regards, >>MW >> >>diff --git a/arm.c b/arm.c >>index 0347166..9d4afcc 100644 >>--- a/arm.c >>+++ b/arm.c >>@@ -260,6 +260,9 @@ arm_init(int when) >> STRUCT_EXISTS("pteval_t")) >> machdep->flags |= PGTABLE_V2; >> >>+ machdep->section_size_bits = _SECTION_SIZE_BITS; >>+ machdep->max_physmem_bits = _MAX_PHYSMEM_BITS; >>+ >> if (symbol_exists("irq_desc")) >> ARRAY_LENGTH_INIT(machdep->nr_irqs, irq_desc, >> "irq_desc", NULL, 0); >> >>-- >>Crash-utility mailing list >>Crash-utility(a)redhat.com >>https://www.redhat.com/mailman/listinfo/crash-utility >> >