XEN and kernel upgrade problems (or maybe a udev issue)

[__henke]

Hello guys!

I'm done beating my head against the google wall, I turn to you guys instead.

I'll start from the beginning:

I run Gentoo on a VPS on a XEN-platform running the latest 2.6 xen-sources (a newer one is masked in portage) kernel with no problem until udev got updated on my system a few days ago. My problem was that I couldn't connect to my server via SSH and I used the control panel from my host to enter the console.

When I tried to start sshd it gave me an error, "unable to locate urandom" or somthing like that. I googled it and I found a solution to create it via "mknod /dev/urandom c 1 9".
Now I could start sshd and connect to the server via ssh, but the system was unable to create tty/vty/pty or whatever so there was no CLI after I logged in. Again turning to google solved this, I just had to install MAKEDEV and then I ran "/sbin/MAKEDEV pty" and "/sbin/MAKEDEV tty". Now I have a fully functional system, but if my server reboots I had to do all that crap again, besides, I want a fully working system.

Finally after some troubleshooting I found the error was udev and the new version didn't support my kernel.

I now faced two options, downgrade udev or upgrade my kernel.

Peace of cake, downgrade udev!

Unfortunately I failed this, trying to mask a few versions... I dont really know how to do this. Mask udev-171 and unmerge udev then reemerge it? So after I tried this for a few hours I turned to upgrading my kernel from 2.6.?? to 3.6.11. since I'm a novice at compiling kernels and so on, I failed, hard. I compiled it without XEN support. yay!

I got my VPS host to comment out my new kernel in grub.conf and got my system up again using the old 2.6 kernel. Now I've been beating my head googling how to compile a xen-supported guest kernel and I think succeeded, but no. My system wouldn't boot again. Got my system back up again and read more on google and I also read about grub kernel fallback option.

Now here is one of my biggest questions.
My 2.6 kernel is a gzipped file and my new 3.6.11 is a executable bzImage and now I'm thinking this is the problem. Something other really unfortunate is that I cant see the console while booting so I'm just guessing here. I have activated kernel crashdumps in the kernel, but can I see them somewhere? I haven't come that far yet in my troubleshooting yet, just read a few articles here and there.

A summary of my questions:
1. Is it possible to safely downgrade udev?
2. Is it really this hard to upgrade kernels on a xen based VPS?
3. What format should my kernel be in? gzip or executable bzimage?
4. I'll paste my grub.conf as soon as I get my system up and running again, but does the grub failover mechanism really work on a xen-VPS?
5. Kernel crashdumps, is this possible?

Sorry in advance for grammar and spelling, its a bit late here.
I really hope someone can help me with this, it would be truly appreciated!

[__henke]

This is my grub.conf, the one with supposed fallback option enbled :S

Code: Select all

default=saved
timeout=5
hiddenmenu
fallback 0 1

title Gentoo Linux 3.6.11
root (hd0,0)
kernel /boot/vmlinuz-3.6.11-gentoo root=/dev/sda1 console=tty1 crashkernel=auto
savedefault fallback

title Gentoo Linux 2.6 fallback
root (hd0,0)
kernel /boot/vmlinuz-2.6.18-xen-r12 root=/dev/sda1 console=tty1
savedefault fallback

--

also, the file difference in the kernels:

Code: Select all

 
file /boot/vmlinuz-2.6.18-xen-r12
/boot/vmlinuz-2.6.18-xen-r12: gzip compressed data, from Unix, last modified: Tue Aug 10 11:17:19 2010, max compression

file /boot/vmlinuz-3.6.11-gentoo
/boot/vmlinuz-3.6.11-gentoo: Linux kernel x86 boot executable bzImage, version 3.6.11-gentoo (root@henkee.se) #3 SMP Thu Jan 3 20:24:47 CET 20, RO-rootFS, swap_dev 0x3, Normal VGA