[Bug 1645501] Re: corefiles not created in armhf chroot on arm64 porter

[Brian Murray]

Setting up gdb (7.11.90.20161005-0ubuntu2) ...
(yakkety-armhf)brian at rugby:~$ gdb --args cat
GNU gdb (Ubuntu 7.11.90.20161005-0ubuntu2) 7.11.90.20161005-git
Copyright (C) 2016 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "arm-linux-gnueabihf".
Type "show configuration" for configuration details.
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>.
Find the GDB manual and other documentation resources online at:
<http://www.gnu.org/software/gdb/documentation/>.
For help, type "help".
Type "apropos word" to search for commands related to "word"...
Reading symbols from cat...(no debugging symbols found)...done.
(gdb) run
Starting program: /bin/cat 
Cannot parse expression `.L954 4 at r4'.
warning: Probes-based dynamic linker interface failed.
Reverting to original interface.

^Z
Program received signal SIGTSTP, Stopped (user).
0xf772f9e4 in read () at ../sysdeps/unix/syscall-template.S:84
84      ../sysdeps/unix/syscall-template.S: No such file or directory.
(gdb) generate-core-file /tmp/my.core
Saved corefile /tmp/my.core

Setting to verification-done.

** Tags removed: verification-needed
** Tags added: verification-done

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to gdb in Ubuntu.
https://bugs.launchpad.net/bugs/1645501

Title:
  corefiles not created in armhf chroot on arm64 porter

Status in gdb package in Ubuntu:
  Fix Released
Status in gdb source package in Precise:
  Invalid
Status in gdb source package in Trusty:
  Triaged
Status in gdb source package in Xenial:
  Triaged
Status in gdb source package in Yakkety:
  Fix Committed

Bug description:
  Impact
  ------
  Its not possible to create a corefile in an armhf chroot on an arm64 system.

  Test Case
  ---------
  On an arm64 system enter an armhf chroot, then
  1) execute "gdb --args cat"
  2) in gdb type run
  3) press Ctrl-Z
  4) generate-core-file /tmp/my.core

  With the current version of gdb you'll see "Unable to fetch floating
  point registers.", with the version in -proposed you'll see "Saved
  corefile".

  Regression Potential
  --------------------
  The corefiles aren't created at all in this scenario so things should improve.

  I'm filing this about gdb per Steve's suggestion, although this could
  be an issue somewhere else.

  I recently discovered that the apport-test-crash
  (https://code.launchpad.net/~daisy-pluckers/error-tracker-deployment
  /test-crashes) crash files produced for armhf are crash files without
  CoreDumps.  This happened sometime between 20160531 and 20161025.
  I've recreated this on the porter-arm64 box with the following minimal
  test case (generate-sigsegv-crash.py is from apport-test-crashes):

  schroot -c yakkety-armhf
  python generate-sigsegv-crash.py cat

  Running this on both armhf and arm64 we can see the following
  different output.

  armhf chroot on porter-armhf:

    47 Program received signal SIGSEGV, Segmentation fault.
    48 0xb6f599e4 in read () at ../sysdeps/unix/syscall-template.S:84
    49 84      ../sysdeps/unix/syscall-template.S: No such file or directory.
    50 (gdb) Saved corefile /tmp/tmp840s08i1/my.core

  armhf chroot on porter-arm64:

    47 Program received signal SIGSEGV, Segmentation fault.
    48 0xf772f9e4 in read () at ../sysdeps/unix/syscall-template.S:84
    49 84      ../sysdeps/unix/syscall-template.S: No such file or directory.
    50 (gdb) Unable to fetch the floating point registers.: Invalid argument.

  Notice how there is no core file save on porter-arm64.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/gdb/+bug/1645501/+subscriptions