Xavier also mentioned in a private email that "foreach bt" shows
nothing for all non-active tasks, so it appears that something has
changed affecting the ia64 unwind facility.  Has anybody else
running ia64 on 2.6.14 kernels seen this?
Thanks,
  Dave
xb wrote:
 Hello,
 I built crash 4.0-2.18 on ia64 platform and run it on a vanilla 2.6.14
 running kernel.
 It starts OK, and has some commands working.
 Unfortunately, it seems that the backtrace command does not do anything
 (calls unwind_v3(), but does nothing) on a live system.
 I just typed:
    bt 1
 to get the init task backtrace (sleeping state).
 crash is very usefull to have such informations on a live system.
 Do you have any idea ?
 Thanks in advance.
 Xavier
 [root@pf37a xb]# bin/crash vmlinux-2.6.14
 crash 4.0-2.18
 Copyright (C) 2002, 2003, 2004, 2005, 2006  Red Hat, Inc.
 Copyright (C) 2004, 2005, 2006  IBM Corporation
 Copyright (C) 1999-2006  Hewlett-Packard Co
 Copyright (C) 2005  Fujitsu Limited
 Copyright (C) 2005  NEC Corporation
 Copyright (C) 1999, 2002  Silicon Graphics, Inc.
 Copyright (C) 1999, 2000, 2001, 2002  Mission Critical Linux, Inc.
 This program is free software, covered by the GNU General Public License,
 and you are welcome to change it and/or distribute copies of it under
 certain conditions.  Enter "help copying" to see the conditions.
 This program has absolutely no warranty.  Enter "help warranty" for details.
 GNU gdb 6.1
 Copyright 2004 Free Software Foundation, Inc.
 GDB is free software, covered by the GNU General Public License, and you are
 welcome to change it and/or distribute copies of it under certain
 conditions.
 Type "show copying" to see the conditions.
 There is absolutely no warranty for GDB.  Type "show warranty" for details.
 This GDB was configured as "ia64-unknown-linux-gnu"...
 unwind_init_v3
      KERNEL: vmlinux-2.6.14
    DUMPFILE: /dev/mem
        CPUS: 6
        DATE: Mon Jan  9 19:14:18 2006
      UPTIME: 48 days, 13:04:50
 LOAD AVERAGE: 0.26, 0.30, 0.14
       TASKS: 125
    NODENAME: pf37a
     RELEASE: 2.6.14
     VERSION: #1 SMP Mon Nov 21 13:27:22 CET 2005
     MACHINE: ia64  (1600 Mhz)
      MEMORY: 31.9 GB
         PID: 7592
     COMMAND: "crash"
        TASK: e00000012c8a0000  [THREAD_INFO: e00000012c8a0d60]
         CPU: 0
       STATE: TASK_RUNNING (ACTIVE)
 crash> bt
 PID: 7592   TASK: e00000012c8a0000  CPU: 0   COMMAND: "crash"
 (active)
 crash> bt 1
 PID: 1      TASK: e0000023ff220000  CPU: 0   COMMAND: "init"
 crash>
 crash> help -m
              flags: 8000352
 (NEW_UNWIND|NEW_UNW_V3|UNW_READ|UNW_PTREGS|UNW_R0|D
 EVMEMRD)
             kvbase: a000000000000000
  identity_map_base: e000000000000000
           pagesize: 65536
          pageshift: 16
           pagemask: ffffffffffff0000
         pageoffset: ffff
          stacksize: 32768
                 hz: 1024
                mhz: 1024
            memsize: 34269102080 (0x7fa990000)
               bits: 64
            nr_irqs: 256
      eframe_search: ia64_eframe_search()
         back_trace: ia64_back_trace_cmd()
 get_processor_speed: ia64_processor_speed()
              uvtop: ia64_uvtop()
              kvtop: ia64_kvtop()
       get_task_pgd: ia64_get_task_pgd()
           dump_irq: ia64_dump_irq()
    get_stack_frame: ia64_get_stack_frame()
      get_stackbase: ia64_get_stackbase()
       get_stacktop: ia64_get_stacktop()
      translate_pte: ia64_translate_pte()
        memory_size: generic_memory_size()
      vmalloc_start: ia64_vmalloc_start()
       is_task_addr: ia64_is_task_addr()
      verify_symbol: ia64_verify_symbol()
         dis_filter: ia64_dis_filter()
           cmd_mach: ia64_cmd_mach()
       get_smp_cpus: ia64_get_smp_cpus()
          is_kvaddr: generic_is_kvaddr()
          is_uvaddr: generic_is_uvaddr()
       verify_paddr: ia64_verify_paddr()
    init_kernel_pgd: NULL
    value_to_symbol: generic_machdep_value_to_symbol()
  line_number_hooks: ia64_line_number_hooks
      last_pgd_read: 0
      last_pmd_read: 0
     last_ptbl_read: 0
                pgd: 600000000013a650
                pmd: 600000000014a660
               ptbl: 600000000015a670
       ptrs_per_pgd: 8192
        cmdline_arg: (null)
           machspec: ia64_machine_specific
                   cpu_data_address: e000000004b00030
                     unimpl_va_mask: 0
                     unimpl_pa_mask: 7ffc000000000000
                                unw: 60000000000de800
                  unw_tables_offset: 8
            unw_kernel_table_offset: 288
                unw_pt_regs_offsets: 224
                       script_index: 0
                       script_cache: 600000000a96c9e0   0% (0 of 0)
                          mem_limit: 0
                      kernel_region: 5
                       kernel_start: a000000100000000
                         phys_start: 4008320 (4000000)
                      vmalloc_start: a000000200000000
                        ia64_memmap: 6000000000ab3780
                    efi_memmap_size: 1728
                   efi_memdesc_size: 48
                        unwind_init: unwind_init_v3()
                             unwind: unwind_v3()
                  dump_unwind_stats: dump_unwind_stats_v3()
                       unwind_debug: unwind_debug_v3()
               ia64_init_stack_size: 0
 crash>   ps
   PID    PPID  CPU       TASK        ST  %MEM     VSZ    RSS  COMM
      0      0   0  a000000100730000  RU   0.0       0      0  [swapper]
  >     0      1   1  e0000001039f0000  RU   0.0       0      0  [swapper]
  >     0      1   2  e000000103a20000  RU   0.0       0      0  [swapper]
  >     0      1   3  e000000103a40000  RU   0.0       0      0  [swapper]
  >     0      1   4  e000000103a60000  RU   0.0       0      0  [swapper]
  >     0      1   5  e000000103a80000  RU   0.0       0      0  [swapper]
      1      0   1  e0000023ff220000  IN   0.0    5184   3648  init
      2      1   0  e0000001039b0000  IN   0.0       0      0  [migration/0]
      3      1   0  e0000023ff230000  IN   0.0       0      0  [ksoftirqd/0]
      4      1   0  e0000001039d0000  IN   0.0       0      0  [watchdog/0]
 .....