>On 11/13/2014 05:01 PM, Atsushi Kumagai wrote: >> Hello Zhou, >> >>> Add description of incomplete elf and kdump-compressed dump file >>> in IMPLEMENTATION. >> >> That's a good idea, thanks Zhou. >> I have some comments. >> >>> Signed-off-by: Qiao Nuohan<qiaonuohan at cn.fujitsu.com> >>> Signed-off-by: Zhou Wenjian<zhouwj-fnst at cn.fujitsu.com> >>> --- >>> IMPLEMENTATION | 76 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++ >>> 1 files changed, 76 insertions(+), 0 deletions(-) >>> >>> diff --git a/IMPLEMENTATION b/IMPLEMENTATION >>> index 2f4cfd6..8f8a945 100644 >>> --- a/IMPLEMENTATION >>> +++ b/IMPLEMENTATION >>> @@ -112,3 +112,79 @@ >>> unsigned long long page_flags; /* page flags */ >>> } page_desc_t; >>> >>> +* The incomplete DUMPFILE >>> + When generating DUMPFILE, if ENOSPACE error happens, the DUMPFILE will be >>> + incomplete. >>> + >>> + - The incomplete kdump-compressed DUMPFILE >>> + >>> + the complete the incomplete >>> + +-----------------------+ +-----------------------+ >>> + | main header | | main header | have incomplete flag >>> + |-----------------------+ |-----------------------+ >>> + | sub header | | sub header | >>> + |-----------------------+ |-----------------------+ >>> + | 1st-bitmap | | 1st-bitmap | >>> + |-----------------------+ |-----------------------+ >>> + | 2nd-bitmap | | 2nd-bitmap | >>> + |-----------------------+ |-----------------------+ >>> + | page header for pfn 0 | | page header for pfn 0 | >>> + | page header for pfn 1 | | page header for pfn 1 | >>> + | : | | : | >>> + | page header for pfn N | | page header for pfn N | The page headers after >>> + | : | | | N don't exist. The >>> + | page header for pfn Z | | | value of it is zero, >>> + |-----------------------| |-----------------------| when try to read it. >>> + | page data (pfn 0) | | page data (pfn 0) | >>> + | page data (pfn 1) | | page data (pfn 1) | >>> + | : | | : | >>> + | page data (pfn N) | | page data (pfn N) | >>> + | : | +-----------------------+ >>> + | page data (pfn Z) | >>> + +-----------------------+ >>> + >>> + The incomplete flag is set into status of disk_dump_header by >>> + status |= DUMP_DH_COMPRESSED_INCOMPLETE >>> + DUMP_DH_COMPRESSED_INCOMPLETE : 0x8 >>> + >>> + The page header and page data are written in pairs. When writting page data >> >> s/writting/writing/ >> >>> + (pfn N+1), if ENOSPACE error happens, the page headers after N won't be >>> + written either. >>> + >>> + If there is no page data dumped into the DUMPFILE, the DUMPFILE can't be >>> + analysed by crash. >>> + >>> + - The incomplete elf DUMPFILE >> >> There is no description of the ELF format itself in this documentation >> unlike the kdump-compressed format, I would be glad if you could write it. >> >>> + >>> + the complete the incomplete >>> + +-------------+ +-------------+ >>> + | elf header | | elf header | have incomplete flag >>> + |-------------+ |-------------+ >>> + | PT_NOTE | | PT_NOTE | >>> + | PT_LOAD(1) | | PT_LOAD(1) | >>> + | : | | : | >>> + | PT_LOAD(N) | | PT_LOAD(N) | The PT_LOAD after N don't exist. >>> + | : | | | The value of it is zero, when try >>> + | PT_LOAD(Z) | | | to read it. >>> + |-------------+ |-------------+ >> >> The whole program header must exist since reserve_diskspace() >> pre-allocates enough space for it, the description above isn't right. >> >The space exists, but since PT_LOAD and segment are written in pairs, >if ENOSPACE happens, the left PT_LOAD won't be generated and won't be >written as well. The space reserved is for the PT_LOAD still in buffer. Oh, it slipped my mind. You are right. Thanks Atsushi Kumagai >-- >Thanks >Zhou Wenjian > >_______________________________________________ >kexec mailing list >kexec at lists.infradead.org >http://lists.infradead.org/mailman/listinfo/kexec
