Hi Troy,

some other package has to be updated together with xen: We do kickstart 
installs of para-VMs using virt-install. This worked fine before the 
kernel+xen update (SL 5.0). Afterwards, it would still work up to the 
point where the guest reboots. Virt-install would consistently tell me:

Guest installation complete... restarting guest.
libvir: Xen Daemon error : POST operation failed: (xend.err "Error 
creating domain: Boot loader didn't return any data!")
exception was: virDomainCreate() failed POST operation failed: (xend.err 
"Error creating domain: Boot loader didn't return any data!")
Domain installation may not have been
successful.  If it was, you can restart your domain
by running 'virsh start ...'; otherwise, please
restart your installation.

Of course virsh start didn't work either, nor did xm create.  This was 
reproducible (at least 3 times). I then updated the remaining packages 
from 5.1 (the host has a fairly minimal installation), and virsh start 
worked immediately.

I append the list of packages that got updated. I still wonder which one 
it is, and unfortunately won't be able to find out for the next week:

Updated: libgcc.x86_64 4.1.2-14.el5
Updated: glibc-common.x86_64 2.5-18.el5.1
Updated: glibc.x86_64 2.5-18.el5.1
Updated: libselinux.x86_64 1.33.4-4.el5
Updated: glibc.i686 2.5-18.el5.1
Updated: device-mapper.x86_64 1.02.20-1.el5
Updated: e2fsprogs-libs.x86_64 1.39-10.el5
Updated: module-init-tools.x86_64 3.3-0.pre3.1.34.el5
Updated: popt.x86_64 1.10.2-47.el5
Updated: audit-libs.x86_64 1.5.5-7.el5
Updated: nspr.x86_64 4.6.5-3.el5
Updated: udev.x86_64 095-14.9.el5
Updated: binutils.x86_64 2.17.50.0.6-5.el5
Updated: audit-libs.i386 1.5.5-7.el5
Updated: libselinux.i386 1.33.4-4.el5
Updated: libgcc.i386 4.1.2-14.el5
Updated: device-mapper.i386 1.02.20-1.el5
Updated: e2fsprogs-libs.i386 1.39-10.el5
Updated: e2fsprogs.x86_64 1.39-10.el5
Updated: initscripts.x86_64 8.45.17.EL-1
Updated: lvm2.x86_64 2.02.26-3.el5
Updated: kpartx.x86_64 0.4.7-12.el5
Updated: dmraid.x86_64 1.0.0.rc13-4.el5
Updated: nspr.i386 4.6.5-3.el5
Updated: nss.x86_64 3.11.7-1.3.el5
Updated: openafs.x86_64 1.4.5-56.SL5
Updated: nscd.x86_64 2.5-18.el5.1
Updated: libstdc++.i386 4.1.2-14.el5
Updated: mesa-libGL.i386 6.5.1-7.5.el5
Updated: audit-libs-python.x86_64 1.5.5-7.el5
Updated: mesa-libGL.x86_64 6.5.1-7.5.el5
Updated: libacl.x86_64 2.2.39-2.1.el5
Updated: bind-libs.x86_64 30:9.3.3-10.el5
Updated: libstdc++.x86_64 4.1.2-14.el5
Updated: libvolume_id.x86_64 095-14.9.el5
Updated: tcp_wrappers.x86_64 7.6-40.4.el5
Updated: gtk2.x86_64 2.10.4-19.el5
Updated: kernel-module-openafs-2.6.18-53.1.4.el5xen.x86_64 1.4.5-56.SL5
Updated: nss.i386 3.11.7-1.3.el5
Installed: device-mapper-multipath.x86_64 0.4.7-12.el5
Updated: sysklogd.x86_64 1.4.1-40.el5
Updated: vixie-cron.x86_64 4:4.1-72.el5
Updated: hwdata.noarch 0.211-1
Updated: libselinux-python.x86_64 1.33.4-4.el5
Updated: nash.x86_64 5.1.19.6-19
Updated: openafs-client.x86_64 1.4.5-56.SL5
Updated: evolution-data-server.x86_64 1.8.0-25.el5
Updated: nss_ldap.i386 253-5.el5
Updated: nss_ldap.x86_64 253-5.el5
Updated: pam_krb5.i386 2.2.14-1
Updated: parted.i386 1.8.1-12.el5
Updated: libuser.x86_64 0.54.7-2.el5.2
Updated: parted.x86_64 1.8.1-12.el5
Updated: pam_krb5.x86_64 2.2.14-1
Updated: cracklib.i386 2.8.9-3.3
Updated: tcp_wrappers.i386 7.6-40.4.el5
Updated: cracklib.x86_64 2.8.9-3.3
Updated: alsa-lib.x86_64 1.0.14-1.rc4.el5
Updated: openafs-compat.x86_64 1.4.5-56.SL5
Updated: mkinitrd.x86_64 5.1.19.6-19
Updated: mkinitrd.i386 5.1.19.6-19
Updated: nss-tools.x86_64 3.11.7-1.3.el5
Updated: conman.x86_64 0.1.9.2-8.el5
Updated: bind-utils.x86_64 30:9.3.3-10.el5
Updated: acl.x86_64 2.2.39-2.1.el5
Updated: audit.x86_64 1.5.5-7.el5
Updated: openafs-krb5.x86_64 1.4.5-56.SL5
Updated: pkinit-nss.x86_64 0.7.3-1.el5
Updated: microcode_ctl.x86_64 1:1.17-1.42.el5
Updated: dhclient.x86_64 12:3.0.5-7.el5
Updated: irqbalance.x86_64 2:0.55-6.el5
Updated: crash.x86_64 4.0-4.6.1
Updated: nfs-utils.x86_64 1:1.0.9-24.el5
Updated: prelink.x86_64 0.3.9-2.1
Updated: autofs.x86_64 1:5.0.1-0.rc2.55
Updated: cpuspeed.x86_64 1:1.2.1-1.48.el5
Updated: ypbind.x86_64 3:1.19-8.el5
Updated: xterm.x86_64 215-5.el5
Updated: ntp.x86_64 4.2.2p1-7.el5
Updated: redhat-menus.noarch 6.7.8-2.el5
Updated: cracklib-dicts.x86_64 2.8.9-3.3
Installed: sos.noarch 1.7-9.1.el5
Updated: Deployment_Guide-en-US.noarch 5.1.0-11
Updated: man-pages.noarch 2.39-10.el5
Updated: rpm-libs.x86_64 4.4.2-47.el5
Updated: hal.x86_64 0.5.8.1-25.el5.1
Updated: rpm.x86_64 4.4.2-47.el5
Updated: policycoreutils.x86_64 1.33.12-12.el5
Updated: redhat-lsb.i386 3.1-12.3.EL
Updated: redhat-lsb.x86_64 3.1-12.3.EL
Updated: rpm-python.x86_64 4.4.2-47.el5
Updated: kudzu.x86_64 1.2.57.1.15-1
Updated: system-config-network-tui.noarch 1.3.99-2.el5
Updated: pm-utils.x86_64 0.99.3-6.el5.17
Updated: selinux-policy.noarch 2.4.6-106.el5.3
Updated: firstboot-tui.noarch 1.4.27.3-1.el5
Updated: selinux-policy-targeted.noarch 2.4.6-106.el5.3
Erased: sysreport
Updated: Deployment_Guide-en-US.noarch 5.1.0-11



-- 
Stephan Wiesand
   DESY - DV -
   Platanenallee 6
   15738 Zeuthen, Germany