Public bug reported:

Based on a year of building and running Ubuntu images on EC2, the
community came to the following specific steps for managing libc6
issues:

    chroot $imagedir apt-get install -y libc6-xen
    echo 'hwcap 0 nosegneg' > $imagedir/etc/ld.so.conf.d/libc6-xen.conf
    chroot $imagedir apt-get remove -y libc6-i686 || true
    chroot $imagedir ldconfig

These steps are only performed on the 32-bit images (after Dapper) and
the /lib/tls directory is left in place.

These steps prevent and fix some warnings as well as serious crashes and
hangs.

I don't claim to understand all the internal workings that are involved
here, so I don't know if these are required for a modern Ubuntu Xen
kernel with Ubuntu Intrepid.

Please do consider them, however, as the current vmbuilder --ec2 image
does at least generate the following warning on boot:

   ***************************************************************
   ***************************************************************
   ** WARNING: Currently emulating unsupported memory accesses  **
   **          in /lib/tls glibc libraries. The emulation is    **
   **          slow. To ensure full performance you should      **
   **          install a 'xen-friendly' (nosegneg) version of   **
   **          the library, or disable tls support by executing **
   **          the following as root:                           **
   **          mv /lib/tls /lib/tls.disabled                    **
   ** Offending process: init (pid=1739)                        **
   ***************************************************************
   ***************************************************************

Note that experience has shown that moving /lib/tls aside as suggested
in the above warning can be very dangerous as future libc6 upgrades will
put it back in place (which has caused system hangs on earlier images).

** Affects: vm-builder (Ubuntu)
     Importance: Undecided
         Status: New

-- 
vmbuilder EC2: Install libc6-xen
https://bugs.launchpad.net/bugs/293067
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