[Bug 490792] [NEW] ARM/Thumb interworking support missing from nanojit

Dave Martin Dave.Martin at arm.com
Tue Dec 1 11:55:44 UTC 2009

Public bug reported:

Binary package hint: xulrunner-1.9.1

The problem here is that the nanojit output tries to call functions in
xulrunner using plain BL instructions, causing the CPU to interpret the
called (Thumb-2) code as ARM... which doesn't work.

The symptoms are random SIGILLs and segfaults in firefox-3.5.

Apparently, the required support has been implemented in mozilla-central for the last few months, but unfortunately there is not a straightforward patch against the current Ubuntu source to fix this :(

Possible workarounds:
 1) Update to the firefox 3.6 / mozilla 1.9.2 branch on mozilla-central (http://hg.mozilla.org/releases/mozilla-1.9.2/ ... it's still in beta though, and there are unresolved issues about openjdk java plugin support --- see https://blueprints.launchpad.net/ubuntu/+spec/desktop-lucid-new-firefox-support-model)
 2) Build all of xulrunner with -marm (firefox may also need -marm --- it depends on whether the nanojit output might call absolutely anything or just support functions in xulrunner)

The most recent relevant commit on mozilla-central is http://hg.mozilla.org/mozilla-central/rev/f8ce8b4d6ce1
It looks like the relevant changes weren't on the mozilla 1.9.1 / firefox 3.5 branch.

$ lsb_release -a
No LSB modules are available.
Distributor ID: Ubuntu
Description:    Ubuntu lucid (development branch)
Release:        10.04
Codename:       lucid

$ apt-cache policy xulrunner-1.9.1 firefox-3.5
  Version table:
 *** 0
        500 http://ports.ubuntu.com/main Packages
        100 /var/lib/dpkg/status
  Installed: 3.5.5+nobinonly-0ubuntu2
  Candidate: 3.5.5+nobinonly-0ubuntu2
  Version table:
 *** 3.5.5+nobinonly-0ubuntu2 0
        500 http://ports.ubuntu.com lucid/main Packages
        100 /var/lib/dpkg/status

** Affects: xulrunner-1.9.1 (Ubuntu)
     Importance: Undecided
         Status: New

** Tags: armel armv7

ARM/Thumb interworking support missing from nanojit
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