Re: [PATCH] makedumpfile: fix max_mapnr issue on system has over 44-bit addressing

HATAYAMA Daisuke
2013-10-08T05:42:28Z

(2013/09/25 17:16), Jingbai Ma wrote:
> On 09/25/2013 08:35 AM, HATAYAMA Daisuke wrote:
>> (2013/09/24 21:49), Jingbai Ma wrote:
>>> This patch will fix a bug of makedumpfile doesn't work correctly on
>>> system
>>> has over 44-bit addressing in compression dump mode.
>>> This bug was posted here:
>>> http://lists.infradead.org/pipermail/kexec/2013-September/009587.html
>>>
>>> This patch will add a new field in struct kdump_sub_header.
>>> unsigned long max_mapnr;
>>>
>>> And the old "unsigned int max_mapnr" in struct disk_dump_header will
>>> not be used anymore. But still be there for compatibility purpose.
>>>
>>> This patch will change the header_version to 6.
>>>
>>> The corresponding patch for crash utility will be sent out separately.
>>>
>>> This patch doesn't change sadump_header.
>>> Because of in sadump file, there is no any sub-header, it has to change
>>> the sadump_header itself.
>>> And if do so, will cause backwards-compatibility issue.
>>> So it could be a separate patch if needed.
>>>
>>> Signed-off-by: Jingbai Ma <jingbai.ma@hp.com>
>>> ---
>>> IMPLEMENTATION | 1 +
>>> diskdump_mod.h | 5 ++++-
>>> makedumpfile.c | 28 ++++++++++++++++++++++------
>>> 3 files changed, 27 insertions(+), 7 deletions(-)
>>>
>>> diff --git a/IMPLEMENTATION b/IMPLEMENTATION
>>> index f0f3135..d576811 100644
>>> --- a/IMPLEMENTATION
>>> +++ b/IMPLEMENTATION
>>> @@ -77,6 +77,7 @@
>>> unsigned long size_note; /* header_version 4 and later */
>>> off_t offset_eraseinfo; /* header_version 5 and later */
>>> unsigned long size_eraseinfo; /* header_version 5 and later */
>>> + unsigned long max_mapnr; /* header_version 6 and later */
>>
>> x86 PAE mode can represents 52-bit physical addresses and so 40-bit
>> physical
>> page frames. On x86_32 unsigned long has 32-bit length only. So, you should
>> define max_mapnr as unsigned long long.
>>
>
> Good catch, I forgot x86 PAE mode also may exceed 32-bit length.
> Will fix it.
>

Though perhaps you've already noticed, both start_pfn and end_pfn in kdump sub
header have 32-bit length on x86_32. These need to be extended to 64-bit length,
too.

/*
* Sub header for KDUMP
* But Common header of KDUMP is disk_dump_header of diskdump.
*/
struct kdump_sub_header {
unsigned long phys_base;
int dump_level; /* header_version 1 and later */
int split; /* header_version 2 and later */
unsigned long start_pfn; /* header_version 2 and later */
unsigned long end_pfn; /* header_version 2 and later */
off_t offset_vmcoreinfo;/* header_version 3 and later */
unsigned long size_vmcoreinfo; /* header_version 3 and later */
off_t offset_note; /* header_version 4 and later */
unsigned long size_note; /* header_version 4 and later */
off_t offset_eraseinfo; /* header_version 5 and later */
unsigned long size_eraseinfo; /* header_version 5 and later */
};

--
Thanks.
HATAYAMA, Daisuke