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. >+ | sec_hdr | | sec_hdr | >+ |-------------+ |-------------+ >+ | elf note | | elf note | >+ |-------------+ |-------------+ >+ | segment(1) | | segment(1) | >+ | : | | : | >+ | segment(N) | | segment(N) | The segment(N) is incomplete. >+ | : | +-------------+ The segments after N don't exist. >+ | segment(Z) | >+ +-------------+ >+ >+ The incomplete flag is set into e_flags of elf_header by >+ e_flags |= DUMP_ELF_INCOMPLETE >+ DUMP_ELF_INCOMPLETE : 0x1 >+ >+ The PT_LOAD and segment are written in pairs. When writting segment(N) s/writting/writing/ Thanks, Atsushi Kumagai >+ , if ENOSPACE error happens, the PT_LOAD after N won't be written >+ either. >+ >+ If there is no segment dumped into the DUMPFILE, the DUMPFILE can't be >+ analysed by crash. >-- >1.7.1 > > >_______________________________________________ >kexec mailing list >kexec at lists.infradead.org >http://lists.infradead.org/mailman/listinfo/kexec
