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

... But I got another error later, which I will report later.


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);
>
>--
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>https://www.redhat.com/mailman/listinfo/crash-utility
>

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On Wed, May 25, 2011 at 8:07 AM, <takuo.koguchi.sw@hitachi.com> wrote:
> 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
>
> ... But I got another error later, which I will report later.
>

Is it possible to provide me a sample vmlinux/vmcore pair which I
could use for testing?

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>... But I got another error later, which I will report later.
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
>
>... But I got another error later, which I will report later.
>
>
>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);
>>
>>--
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>>Crash-utility@redhat.com
>>https://www.redhat.com/mailman/listinfo/crash-utility
>>
>

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On Wed, May 25, 2011 at 10:11 AM, <takuo.koguchi.sw@hitachi.com> wrote:
>>... But I got another error later, which I will report later.
> 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.
>

Please check your platforms
arch/arm/mach-<yourmach>/include/mach/memory.h and set both
_SECTION_SIZE_BITS and _MAX_PHYSMEM_BITS to be the same as defined in
the header. If crash works with the correct values, we just need to
find out some way of guessing these.

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Hi Dave,
>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) ?

Now I am quite sure the definition of NR_SECTION_ROOTS() is wrong.
In the upstream kernel, I found the following
include/linux/mmzone.h
...
994 #define SECTION_NR_TO_ROOT(sec) ((sec) / SECTIONS_PER_ROOT)
995 #define NR_SECTION_ROOTS DIV_ROUND_UP(NR_MEM_SECTIONS, SECTIONS_PER_ROOT)
996 #define SECTION_ROOT_MASK (SECTIONS_PER_ROOT - 1)

and
include/kernel.h DIV_ROUND_UP is defined as follows,
58 #define DIV_ROUND_UP(n,d) (((n) + (d) - 1) / (d))

I hope you can take care of this.


By the way, I think _SECTION_SIZE_BITS issue is a separate issue.


Best Regard,

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
>
>... But I got another error later, which I will report later.
>
>
>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);
>>
>>--
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>>Crash-utility@redhat.com
>>https://www.redhat.com/mailman/listinfo/crash-utility
>>
>

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