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

(2013/09/25 17:16), Jingbai Ma wrote: <cut> >> >>> @@ -5153,10 +5160,11 @@ write_kdump_header(void) >>> * Write common header >>> */ >>> strncpy(dh->signature, KDUMP_SIGNATURE, strlen(KDUMP_SIGNATURE)); >>> - dh->header_version = 5; >>> + dh->header_version = 6; >>> dh->block_size = info->page_size; >>> dh->sub_hdr_size = sizeof(kh) + size_note; >>> dh->sub_hdr_size = divideup(dh->sub_hdr_size, dh->block_size); >>> + /* dh->max_mapnr may be truncated here, full 64bit in kh.max_mapnr */ >>> dh->max_mapnr = info->max_mapnr; >> >> dh->max_mapnr = MIN(info->max_mapnr, UINT_MAX) seems better for old >> versions of crash utitlity. >> > > Although change this value to UINT_MAX doesn't help the old crash > utility very much. At least this special value will tell the user > something happened. > Will fix it. > > This is the largest page frame number old crash utilities can represent, not special value. By this, old crash utilities can read at least the pages less than UINT_MAX, which is better than making dh->max_mapnr overflow; then dh->max_mapnr would typically become a small number.