Re: [gentoo-user] New kernel does not boot up on remote host

[Galevsky <galevsky@gmail.com>]

2007/7/5, Dan Farrell <dan@spore.ath.cx>:
> On Thu, 5 Jul 2007 18:40:20 +0200
> Galevsky <galevsky@gmail.com> wrote:
>
> > 2007/7/5, Albert Hopkins <marduk@gentoo.org>:
> > > On Thu, 2007-07-05 at 11:36 +0200, Galevsky wrote:
> > > > Many thanks for you suggestion. I tried a boot with no fall back,
> > > > but nothing added neither to boot.log nor to dmesg. I am sure to
> > > > target the right kernel image with no typo into grub.conf . This
> > > > new kernel is a =xen-sources-2.6.16.49, and I configured it
> > > > making an oldconfig based on current =gentoo-sources-2.6.20
> > > > running kernel. So, errors cannot come from drivers or such
> > > > things, but specific xen options. Does anyone know any xen option
> > > > able to prevent the kernel to boot up ?
> > >
> > > I guess I (still) don't understand what your issue is.  So I went
> > > back and read your original post.  Maybe I misunderstood it.
> > >
> > >       * What do you mean by "remote host"?
> >
> > I rent a dedicated host. Thus, I have no physical access to the
> > machine. And the reason why I used the fall-back feature into grub is
> > to avoid the use of a boring rescue system (via a web interface) to
> > take back the control of a not-responding box.
> >
> > >       * If your box "does not boot" how would you expect to see a
> > >         boot.log or dmesg ? They don't exist if the system has not
> > >         booted.  In fact "does not boot" implies that you can't
> > > even log in to check for dmesg or boot logs.  Perhaps you can
> > > explain what it is exactly you mean by "does not boot".
> >
> > When I try to boot on the new kernel, I set it as the "default" one in
> > grub.conf and reboot the box. And I wait for a few minutes. Then I try
> > to log on, praying to find the box responding.
> >
> > First, with grub fall-back activated, the boot had fallen back and I
> > was able to read the logs that contained the running kernel logs, but
> > no info about the kernel boot that failed. That was the matter of my
> > first mail: how to read  the reasons of the first kernel-boot-attempt
> > failure.
> >
> > Secondly, you advised me to turn fall back off. I do. The box is no
> > more responding after reboot, and I have to launch the "rescue system"
> > to log on my box, and read the /var/log/*. I thought previously that
> > some pb happened -I didn't know when exactly-... and was waiting for
> > more info in log files. But files were empty. So, I conclude that the
> > boot procedure failed (and you too ;o)).
> >
> > Finally, I have to find out why my kernel is not booting. I tuned up
> > well my previous kernel, a gentoo-sources-2.6.20 -this kernel runs
> > currently my box very well- and the kernel I want to boot now is a
> > xen-sources-2.6.16. I made an oldconfig on /proc/config.gz of the
> > 2.6.20 running kernel, and fill in xen-dom0 specific options as
> > indicated on the wiki tutorial [1]. So, I guess I did something wrong
> > with the dom0 xen config, and asked for advice on xen specific options
> > with my second post.
> >
> > >       * Usually there is an error message on the console if there
> > > is a boot loader/kernel issue with booting.
> > >       * Also you never posted your grub.conf.
> > >
> > > So hopefully you can come up with a specific explanation of "does
> > > not boot" as well as your config and any console messages you get.
> > > Else this becomes a "blind leading the blind" issue.
> >
> > I have no console message to provide you, I just know that my remote
> > box is not responding when I try to boot another kernel (If you know
> > the way to get logs, I'll be grateful :o)). And I checked the
> > /var/log/* to be sure that the kernel was not running but just missing
> > any network feature so that I could not log on the box despite the
> > kernel was actually running.
> >
> > As for my grub.conf + 'ls -l /boot' , I will provide you in a while (I
> > need to go home before), but I am not sure it is relevant. (just to
> > check for typo I guess).
> >
> > > --
> > > Albert W. Hopkins
> > >
> > > --
> > > gentoo-user@gentoo.org mailing list
> >
> > Many thanks to take care of my problem :o)
> >
> > Gal'
> >
> > [1]: http://gentoo-wiki.com/HOWTO_Xen_and_Gentoo
>
> from /etc/conf.d/rc:
> # RC_BOOTLOG will generate a log of the boot messages shown on the
> console. # Useful for headless machines or debugging.  You need to
> emerge the # app-admin/showconsole package for this to work.  Note that
> this probably # won't work correctly with boot splash.
>
> RC_BOOTLOG="no"
>
> I recommend you install showconsole and set RC_BOOTLOG to yes, that
> might help you.  It is possible that maybe something as mundane as
> networking is failing for a stupid reason, and therefore you cant get
> to the computer because it cant finish booting.
> --
> gentoo-user@gentoo.org mailing list
>
>

Thank you Dan, but I did it before, and boot.log remains empty. In
fact, the new kernel boot turns on like grub couldn't find the kernel
image....

Hereafter my /boot content:

sd-4421 boot # ll /boot
total 13M
-rw-rw-r-- 1 root root 767k Jul  6 00:02
System.map-2.6.16.49-xendedibox_r6_final
-rw-r--r-- 1 root root 929k Jun 16 19:29 System.map-2.6.20-gentoo-r8
lrwxrwxrwx 1 root root    1 Apr 30 19:40 boot -> ./
-rw-rw-r-- 1 root root  31k Jul  6 00:02 config-2.6.16.49-xendedibox_r6_final
-rw-r--r-- 1 root root  34k Jun 16 19:29 config-2.6.20-gentoo-r8
-rw-r--r-- 1 root root  753 Jul  4 23:30 gentoo-sources-2.6.18
drwxr-xr-x 2 root root 1.1k Jun 16 16:58 grub/
drwx------ 2 root root  13k Apr 30 19:40 lost+found/
drwxr-xr-x 2 root root 1.1k Jun 16 23:21 ref/
-rw-r--r-- 1 root root 5.9M Jul  6 00:02
vmlinux-syms-2.6.16.49-xendedibox_r6_final
lrwxrwxrwx 1 root root   37 Jul  6 00:02 vmlinuz-2.6-xen ->
vmlinuz-2.6.16.49-xendedibox_r6_final
lrwxrwxrwx 1 root root   37 Jul  6 00:02 vmlinuz-2.6.16-xen ->
vmlinuz-2.6.16.49-xendedibox_r6_final
-rw-r--r-- 1 root root 2.4M Jul  6 00:02 vmlinuz-2.6.16.49-xendedibox_r6_final
-rw-r--r-- 1 root root 2.4M Jun 16 19:29 vmlinuz-2.6.20-gentoo-r8

and my grub.conf:

### START (grub.conf)
sd-4421 boot # cat /boot/grub/grub.conf
# Customized boot procedure

default 0
timeout 1
#fallback 1 2

title Gentoo Linux 2.6.16-gentoo_xen_dom0
  root (hd0,0)
  kernel /boot/vmlinuz-2.6-xen ro root=/dev/sda2


title Gentoo Linux 2.6.20-r8
  root (hd0,0)
  kernel /boot/vmlinuz-2.6.20-gentoo-r8 ro root=/dev/sda2


title Gentoo Linux 2.6.18-r4-dedibox_r6_final
  root (hd0,0)
  kernel /boot/ref/2.6.18-gentoo-r4dedibox_r6_final ro root=/dev/sda2
### END (grub.conf)

Well, let's try a boot on kernel /boot/vmlinuz-2.6-xen

=> box not responding..... and via the rescue system:

# ls /mnt/sda2/var/log/
portage   user.log  xen
# more  /mnt/sda2/var/log/user.log
Jul  6 00:12:30 sd-4421 shutdown[4571]: shutting down for system reboot

thus no log at all (xen log also empty).


Gal'
-- 
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