Topic: Kernal Question

[Teviot]

Hi

I currently have 4 kernal optins at boot up.  2 SME and 2 Centos.

Which one should I use and how do I select it by default?

I think this is my problem that I had here http://forums.contribs.org/index.php?topic=34761.0

Thanks in advance

[bpivk]

Options should be enabled by default.
But can you list them?

[mercyh]

Look here:

http://forums.contribs.org/index.php?topic=34399.0

and here:

http://forums.contribs.org/index.php?topic=34532.0

[Teviot]

Thanks for those threads Guys

Code: [Select]

Which one should I use and how do I select it by default?


I have read several post as suggested and come up with the following results

Code: [Select]

[root@gateway ~]# cat /proc/cpuinfo
processor       : 0
vendor_id       : GenuineIntel
cpu family      : 15
model           : 3
model name      : Intel(R) Celeron(R) CPU 2.66GHz
stepping        : 4
cpu MHz         : 2661.733
cache size      : 256 KB
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 5
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe pni monitor ds_cpl cid xtpr
bogomips        : 5326.07

[root@gateway ~]# uname -a
Linux gateway 2.6.9-34.ELsmp #1 SMP Wed Mar 8 00:27:03 CST 2006 i686 i686 i386 GNU/Linux
[root@gateway ~]#

Now all I need is instruction on how to change thing so that when the server reboots, it selects the correct kernal. Could somebody tell me how to find the file I need to edit and which bits to change?

[mercyh]

You will need to boot with a monitor attached to the server itself. From the GRUB boot screen select the correct kernel. GRUB will boot this kernel by default after this.

Another thread  

http://forums.contribs.org/index.php?topic=33780.0

the kernel can be selected at the screen with the white penguin. If you have a fast machine it will go past pretty quick so you will need to watch for it. You want to boot the latest version of the kernel. Do not be mislead by the Centos versus SME labels. The update does not relable the kernel as SME so the Centos kernels that you see are SME kernels. The multiprocessor version is the .ELsmp version and the single processor version is the .EL version.

[SARK devs]

Hi

Kernels are installed in parallel, so you can always go back to a previous kernel (as long as you don't delete the old one).  The default kernel together with details of each available kernel can be found in  /boot/grub/grub.conf.  Here's how mine looks...

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[root@sam2 ~]# cat /boot/grub/grub.conf
# grub.conf generated by anaconda
#
# Note that you do not have to rerun grub after making changes to this file
# NOTICE:  You have a /boot partition.  This means that
#          all kernel and initrd paths are relative to /boot/, eg.
#          root (hd0,0)
#          kernel /vmlinuz-version ro root=/dev/main/root
#          initrd /initrd-version.img
#boot=/dev/hda
default=0
timeout=5
splashimage=(hd0,0)/grub/splash.xpm.gz
hiddenmenu
title CentOS (2.6.9-42.0.3.EL)
        root (hd0,0)
        kernel /vmlinuz-2.6.9-42.0.3.EL ro root=/dev/main/root
        initrd /initrd-2.6.9-42.0.3.EL.img
title SME Server (2.6.9-34.ELsmp)
        root (hd0,0)
        kernel /vmlinuz-2.6.9-34.ELsmp ro root=/dev/main/root
        initrd /initrd-2.6.9-34.ELsmp.img
title SME Server-up (2.6.9-34.EL)
        root (hd0,0)
        kernel /vmlinuz-2.6.9-34.EL ro root=/dev/main/root
        initrd /initrd-2.6.9-34.EL.img


The default kernel (beginning with zero) is specified in the default tuple.

You can just change it with your favourite editor. So, in the above case if I wanted to start -34.ELsmp then I would set the default to 1.

You should only need to resort to connecting tubes and keyboards if you get it wrong and linux fails to boot.  Then you'll need to press the spacebar when Tux flashes by!!

[mercyh]

Selintra,

Thanks for that info. I have seen it before but it didn't register. I have a server that is quite difficult to access to connect a monitor and keyboard. This will make it easier in the future if I need to select a different kernel.

Royce Holdeman

[byte]

But will changing the default number make a difference? reason I ask is that I manually changed kernel with a kb and monitor but I still see the default as a different one to the kernel which is booting.

For example i choose... 34ELsmp but in the grub.conf the number is set to 34.02ELsmp so when I come to reboot it still selects the one i manually choose by pressing return on the computer.