[Beowulf] PXE/TFTP and Xen Kernel Issues

Bernard Li bernard at vanhpc.org
Wed Dec 16 19:13:08 EST 2009


Hi Jess:

With Xen-based kernels, you should be using the xen.gz "kernel"
instead of vmlinuz.  Here's what a grub entry looks like for booting
Xen-based kernels:

title CentOS (2.6.18-164.el5xen)
	root (hd0,0)
	kernel /xen.gz-3.4.0
	module /vmlinuz-2.6.18-164.el5xen ro root=/dev/VolGroup00/LogVol00
	module /initrd-2.6.18-164.el5xen.img

Good luck!

Cheers,

Bernard

On Tue, Dec 15, 2009 at 2:22 PM, Jess Cannata <jac67 at georgetown.edu> wrote:
> 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
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