[Crash-utility] Question for ARM developers/users w/respect to makedumpfile

[Dave Anderson]

Hey guys,

I've completed the implementation of a new "crash --log vmcore"
option that dumps the kernel log buffer contents from ELF kdump
vmcores and compressed kdump vmcores using the VMCOREINFO data
that's contained in an ELF note in the original /proc/vmcore,
and which makedumpfile copies into the the compressed kdump
header as well.

It works well on all arches except ARM, more specifically
with ARM compressed kdumps.  (It does works OK with the one
ARM ELF vmcore I have).

But I only have two sample ARM vmcore files that are compressed
kdumps.  In both cases, it's pretty obvious that the header 
contains vmcoreinfo data, for example:
 
 $ strings vmcore.v2 
 KDUMP   
 Linux
 (none)
 2.6.38-rc2-00274-g1f0324c-dirty
 #3 SMP Fri Jan 28 09:37:08 EET 2011
 armv7l
 (none)
 iC\I
 OSRELEASE=2.6.38-rc2-00274-g1f0324c-dirty
 PAGESIZE=4096
 SYMBOL(init_uts_ns)=c0590368
 SYMBOL(node_online_map)=c058cc2c
 SYMBOL(swapper_pg_dir)=c0004000
 SYMBOL(_stext)=c0008000
 SYMBOL(vmlist)=c0b2a4a8
 SYMBOL(mem_map)=c0b2a430
 SYMBOL(contig_page_data)=c05eb580
 SIZE(page)=32
 SIZE(pglist_data)=1792
 SIZE(zone)=832
 SIZE(free_area)=44
 SIZE(list_head)=8
 SIZE(nodemask_t)=4
 OFFSET(page.flags)=0
 OFFSET(page._count)=4
 OFFSET(page.mapping)=16
 ...
 
But the new "crash --log vmcore" option fails because it
cannot access the vmcoreinfo data above:

  $ crash --log vmcore.v2

  crash: vmcore.v2: no VMCOREINFO section

  $

If I bring up a crash session with that dumpfile, and dump the
compressed kdump header, I see that it was created by makedumpfile 
using header version 3, which means that vmcoreinfo data is included:

 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 */
 };
 
But note that in the actual dumpfile header dump, the "offset_vmcoreinfo" and 
"size_vmcoreinfo" kdump_sub_header fields are both set to 0:
 
 crash> help -n
 diskdump_data: 
           filename: vmcore.v2
              flags: 6 (KDUMP_CMPRS_LOCAL|ERROR_EXCLUDED) 
                dfd: 3
                ofp: 4e876a00
       machine_type: 40 (EM_ARM)
 
             header: 9a178c0
            signature: "KDUMP   "
       header_version: 3
              utsname:
                sysname: Linux
               nodename: (none)
                release: 2.6.38-rc2-00274-g1f0324c-dirty
                version: #3 SMP Fri Jan 28 09:37:08 EET 2011
                machine: armv7l
             domainname: (none)
            timestamp:
                 tv_sec: 495c4369
                tv_usec: 0
               status: 0 ()
           block_size: 4096
         sub_hdr_size: 1
        bitmap_blocks: 4
            max_mapnr: 65536
     total_ram_blocks: 0
        device_blocks: 0
       written_blocks: 0
          current_cpu: 0
              nr_cpus: 1
       tasks[nr_cpus]: 0
 
         sub_header: 0 (n/a)
 
   sub_header_kdump: 9a188c8 
            phys_base: 80000000
           dump_level: 31 (0x1f) (DUMP_EXCLUDE_ZERO|DUMP_EXCLUDE_CACHE|DUMP_EXCLUDE_CACHE_PRI|DUMP_EXCLUDE_USER_DATA|DUMP_EXCLUDE_FREE)
    offset_vmcoreinfo: 0 (0x0)
      size_vmcoreinfo: 0 (0x0)
 
  ... [ cut ] ...

     page_cache_buf: 9a21928
        evict_index: 11
          evictions: 219
           accesses: 2996
       cached_reads: 2761 (92%)
        valid_pages: 9a218e0
 crash> 
  
I'm wondering whether that's the case with all ARM compressed
kdump files?  Or maybe the dumps I have were created during early 
development of ARM kexec/kdump?  Or is it a bug with the 
makedumpfile facility on ARM? 

So my question is, do any of you have an ARM compressed kdump that 
you can verify has its "offset_vmcoreinfo" and "size_vmcoreinfo"
fields set?

Thanks,
  Dave