[Crash-utility] Re: [PATCH] crash: execution machine pagesize differs

This patch allows a machine to read a dump when that dump was taken on a machine with a larger page size. e.g. we had a dump of a 64k pagesize system, and ran crash on a machine with a 16k pagesize. Diffed against crash-4.0-7.6 Signed-off-by: Cliff Wickman <cpw(a)sgi.com&gt;

--- diskdump.c | 25 +++++++++++++++++++------ tools.c | 2 ++ 2 files changed, 21 insertions(+), 6 deletions(-) Index: crash-4.0-7.6.ia64/diskdump.c =================================================================== --- crash-4.0-7.6.ia64.orig/diskdump.c +++ crash-4.0-7.6.ia64/diskdump.c @@ -107,7 +107,7 @@ static int read_dump_header(char *file) struct disk_dump_sub_header *sub_header = NULL; struct kdump_sub_header *sub_header_kdump = NULL; int bitmap_len; - const int block_size = (int)sysconf(_SC_PAGESIZE); + int block_size = (int)sysconf(_SC_PAGESIZE); off_t offset; const off_t failed = (off_t)-1; ulong pfn; @@ -165,12 +165,25 @@ static int read_dump_header(char *file) machine_type_mismatch(file, "PPC64", NULL, 0)) goto err; - if (header->block_size != block_size) { - error(INFO, "%s: block size in the dump header does not match" - " with system page size\n", - DISKDUMP_VALID() ? "diskdump" : "compressed kdump"); - goto err; + /* + * Up to here, the header was assumed to be one page in size. + * We checked utsname and signature, which are up front in the + * header. But all of the task array may not have been entirely + * read if the executing machines's page size is smaller than that + * of the dumped machine. + * Re-read the entire header if its block_size is bigger than the + * executing machine's page size. + */ + if (header->block_size > block_size) { + block_size = header->block_size; + free(header); + if ((header = malloc(block_size)) == NULL) + error(FATAL, + "diskdump / compressed kdump: cannot malloc block_size buffer\n"); + lseek(dd->dfd, 0, SEEK_SET); + read(dd->dfd, header, block_size); } + dd->block_size = block_size; dd->block_shift = ffs(block_size) - 1;