Am attempting to update a RHEL4 domU from a custom created Xen kernel (created before RHEL5) to a supported kernel (2.6.9-55.0.9.ELxenU) and RHEL5 host without success. For some reason, the kernel can no longer find xvda. Boots fine on the old kernel and host, so I'm at a bit of a loss. Host has other domUs booted off the same SAN, with no security restrictions, so I don't see how it could be hardware. Copy of configs and partial debug log below. Ideas?

Conf:
name = "do5"
memory = "1024"
disk = [ 'phy:/dev/mpath/msa-mpathv0p1,xvda,w', ]
vif = [ 'mac=00:16:3e:55:a5:65, bridge=xenbr2' ]
vfb = ["type=vnc,vncunused=1"]
bootloader="/usr/bin/pygrub"
vcpus=1

Grub:
root (hd0,0)
kernel /vmlinuz-2.6.9-55.0.9.ELxenU ro root=/dev/xvda2 rhgb quiet
initrd /initrd-2.6.9-55.0.9.ELxenU.img

Debug:
[2007-10-30 12:41:21 xend.XendDomainInfo 4121] DEBUG (XendDomainInfo:190) XendDomainInfo.create(['vm', ['name', 'do5'], ['memory', '1024'], ['vcpus', 1], ['bootloader', '/usr/bin/pygrub'], ['image', ['linux', ['ramdisk', '/var/lib/xen/initrd.MpxKQP'], ['kernel', '/var/lib/xen/vmlinuz.6u2e9w'], ['args', 'ro root=/dev/xvda2 rhgb quiet']]], ['device', ['vbd', ['uname', 'phy:/dev/mpath/msa-mpathv0p1'], ['dev', 'xvda'], ['mode', 'w']]], ['device', ['vif', ['bridge', 'xenbr2'], ['mac', '00:16:3e:55:a5:65']]], ['device', ['vkbd']], ['device', ['vfb', ['vncunused', '1'], ['type', 'vnc'], ['display', 'localhost:10.0'], ['xauthority', '/root/.Xauthority']]]])
[2007-10-30 12:41:21 xend.XendDomainInfo 4121] DEBUG (XendDomainInfo:296) parseConfig: config is ['vm', ['name', 'do5'], ['memory', '1024'], ['vcpus', 1], ['bootloader', '/usr/bin/pygrub'], ['image', ['linux', ['ramdisk', '/var/lib/xen/initrd.MpxKQP'], ['kernel', '/var/lib/xen/vmlinuz.6u2e9w'], ['args', 'ro root=/dev/xvda2 rhgb quiet']]], ['device', ['vbd', ['uname', 'phy:/dev/mpath/msa-mpathv0p1'], ['dev', 'xvda'], ['mode', 'w']]], ['device', ['vif', ['bridge', 'xenbr2'], ['mac', '00:16:3e:55:a5:65']]], ['device', ['vkbd']], ['device', ['vfb', ['vncunused', '1'], ['type', 'vnc'], ['display', 'localhost:10.0'], ['xauthority', '/root/.Xauthority']]]]
[2007-10-30 12:41:21 xend.XendDomainInfo 4121] DEBUG (XendDomainInfo:397) parseConfig: result is {'shadow_memory': None, 'start_time': None, 'uuid': None, 'on_crash': None, 'on_reboot': None, 'localtime': None, 'image': ['linux', ['ramdisk', '/var/lib/xen/initrd.MpxKQP'], ['kernel', '/var/lib/xen/vmlinuz.6u2e9w'], ['args', 'ro root=/dev/xvda2 rhgb quiet']], 'on_poweroff': None, 'bootloader_args': None, 'cpus': None, 'name': 'do5', 'backend': [], 'vcpus': 1, 'cpu_weight': None, 'features': None, 'vcpu_avail': None, 'memory': 1024, 'device': [('vbd', ['vbd', ['uname', 'phy:/dev/mpath/msa-mpathv0p1'], ['dev', 'xvda'], ['mode', 'w']]), ('vif', ['vif', ['bridge', 'xenbr2'], ['mac', '00:16:3e:55:a5:65']]), ('vkbd', ['vkbd']), ('vfb', ['vfb', ['vncunused', '1'], ['type', 'vnc'], ['display', 'localhost:10.0'], ['xauthority', '/root/.Xauthority']])], 'bootloader': '/usr/bin/pygrub', 'cpu': None, 'maxmem': None}
[2007-10-30 12:41:21 xend.XendDomainInfo 4121] DEBUG (XendDomainInfo:1264) XendDomainInfo.construct: None
[2007-10-30 12:41:21 xend.XendDomainInfo 4121] DEBUG (XendDomainInfo:1296) XendDomainInfo.initDomain: 9 1.0
[2007-10-30 12:41:21 xend 4121] DEBUG (balloon:127) Balloon: 1049112 KiB free; need 1048576; done.
[2007-10-30 12:41:21 xend 4121] INFO (image:136) buildDomain os=linux dom=9 vcpus=1
[2007-10-30 12:41:21 xend 4121] DEBUG (image:199) dom            = 9
[2007-10-30 12:41:21 xend 4121] DEBUG (image:200) image          = /var/lib/xen/vmlinuz.6u2e9w
[2007-10-30 12:41:21 xend 4121] DEBUG (image:201) store_evtchn   = 1
[2007-10-30 12:41:21 xend 4121] DEBUG (image:202) console_evtchn = 2
[2007-10-30 12:41:21 xend 4121] DEBUG (image:203) cmdline        =  ro root=/dev/xvda2 rhgb quiet
[2007-10-30 12:41:21 xend 4121] DEBUG (image:204) ramdisk        = /var/lib/xen/initrd.MpxKQP
[2007-10-30 12:41:21 xend 4121] DEBUG (image:205) vcpus          = 1
[2007-10-30 12:41:21 xend 4121] DEBUG (image:206) features       =
[2007-10-30 12:41:21 xend 4121] DEBUG (blkif:24) exception looking up device number for xvda: [Errno 2] No such file or directory: '/dev/xvda'