[Beowulf] PXE/TFTP and Xen Kernel Issues

[Jess Cannata]

I'm having a problem booting Xen kernels via PXE. I want to boot a 
machine via PXE that will then host Xen virtual machines. The client 
machine PXE boots, receives the pxelinux.0 file, and then grabs the Xen 
kernel (vmlinuz-2.6.18-164.6.1.el5xen). However, it can never load the 
Xen kernel. On the client, I get the following error:

Invalid or corrupt kernel image.

I have tried the following three kernels (two stock Centos kernels and 
one custom compiled kernel) and only the Xen kernel fails:

-rw-r--r-- 1 root root 2030154 Dec 10 15:28 vmlinuz-2.6.18-164.6.1.el5xen
-rw-r--r-- 1 root root 1932284 Sep 25 16:17 vmlinuz-2.6.18-164.el5
-rw-r--r-- 1 root root 3277584 Dec 10 15:29 vmlinuz-2.6.27.15-jw-node

The others load without error. I have checked multiple times that the 
Xen kernel is not corrupt via md5sums and by booting it via grub. It 
just seems not to like the PXE system. Here is a snippet of the dnsmasq 
log to show that the file is sent correctly to the client:

Dec 11 04:12:57 julie dnsmasq[9117]: TFTP sent /tftpboot/pxelinux.0 to 
192.168.0.6
Dec 11 04:12:57 julie dnsmasq[9117]: TFTP sent 
/tftpboot/pxelinux.cfg/default to 192.168.0.6
Dec 11 04:12:57 julie dnsmasq[9117]: TFTP sent 
/tftpboot/vmlinuz-2.6.18-164.6.1.el5xen to 192.168.0.6

I have tried three different systems for the DHCP, TFTP, and PXE Servers 
(using stock RHEL/Centos packages). Here are the specs:

System 1
Centos 5.4 (64-bit) with nvidia Ethernet adapters
dnsmasq for both DHCP and TFTP Servers
syslinux for PXE

System 2
Centos 5.4 (64-bit) with e1000 Ethernet adapters
dnsmasq for both DHCP and TFTP Servers
syslinux for PXE

System 3
Centos 5.3 (32-bit) with e1000 Ethernet adapters (trying 32-bit version 
of the Xen kernel)
Config One:
dnsmasq for both DHCP and TFTP Servers
syslinux for PXE

Config Two:
dnsmasq for DHCP Server
tftp-server for TFTP Server
syslinux for PXE

The client machines use the same hardware as the servers. I haven't seen 
anything about Xen kernels having issues with PXE. Before I start trying 
different flavors of Linux, I'm curious if anyone else has seen or heard 
of this problem.

Many thanks in advance.

Jess