[Crash-utility] crash version 4.0-4.1 is available

[Dave Anderson]

- Implemented dependable backtraces for the x86_64 architecture. (!!!)
  This feature builds upon the current "low_budget" backtrace function,
  and also required the fix for the BUG()/ud2a disassembly problem
  addressed in 4.0-3.22.  It does not require kernel unwind support,
  but rather it calculates function framesizes by disassembling the
  code from the beginning of the function to the point where it calls
  the next function, parsing for add or sub instructions on the rsp,
  and for push and pop instructions, thereby determining the framesize
  of the function at the point of the call.  This is similar to what is
  done for x86, but requires far less hackery.  You will notice a slight
  hitch the first time a "bt" is done on a task, but for each text
  return address in any backtrace, its framesize is cached for all
  subsequent instances.  It also accounts for backtrace text return
  addresses from the .text.lock section, by appending "(via function)"
  to the end of the frame line.  Also, because it layers on top of the
  current backtrace code, it does not compromise the capability of
  switching between the process, IRQ, and exception stacks.  That all
  being said, 100% accuracy cannot be guaranteed.  But for the ~30
  sample dumpfiles I keep around for x86_64 testing, I cannot find any
  obviously invalid backtraces.  However, if there is any doubt, the
  "bt -o" option will perform backtraces using the "old" manner; and
  "bt -O" will force the old manner to always be used.  Of course the
  "bt -t" and "bt -T" options are still available.  It's interesting to
  redirect the output of "foreach bt" to a file using this version, and
  then compare it with the output from an older version.
  (anderson at redhat.com)

- Fix for s390 and s390x backtrace commands to recognize the kernel
  structure name change from "runqueue" to "rq".
  (holzheu at linux.vnet.ibm.com)

- Merged fourth round of "xencrash" patches, which allows a crash
  session to alternatively be brought up against the xen-syms
  binary instead of a vmlinux kernel.  This patch enhances the
  "doms" command display contents, and adds support to access the
  ia64 frame table virtual address space so that the page_info table
  can be accessed.  (oda at valinux.co.jp)


Download from: http://people.redhat.com/anderson