[gentoo-user] Do I need the vmlinuz symbolic link with Grub?

[gentoo-user] Do I need the vmlinuz symbolic link with Grub?

[Daevid Vincent]

Somehow net-wireless/madwifi-driver has broken on me (0.1_pre20050420-r1),
so I thought I'd recompile it. No luck. So I thought, maybe my kernel source
was different than my actual kernel (2.6.10-gentoo-r6), so I ran: 
"make bzImage modules modules_install"

Copied and renamed the bzImage file over to /boot and all that jazz.

But I don't think I'm getting the right kernel as the date for my kernel is
today, but my vmlinuz is older.

How is that symlink created? And how is the vmlinuz-2.6.10-gentoo-r6
created? What happens if I rm that symlink or the file? Is my system
unbootable?

locutus ~ # ll /boot
total 9896
drwxr-xr-x   5 root root    1024 Aug 30 18:54 .
drwxr-xr-x  21 root root    4096 Aug  2 19:31 ..
lrwxr-xr-x   1 root root      27 Jul 21 19:55 System.map ->
System.map-2.6.10-gentoo-r6
-rw-r--r--   1 root root 1097083 Jul 21 19:55 System.map-2.6.10-gentoo-r6
lrwxrwxrwx   1 root root       1 Sep  4  2004 boot -> .
lrwxr-xr-x   1 root root      34 Jul 21 19:56 config ->
config-kernel-2.6.10-gentoo-r6-cpu
-rw-r--r--   1 root root   34887 Aug 30 12:16
config-kernel-2.6.10-gentoo-r6-cpu
-rw-r--r--   1 root root  602620 Nov 14  2004 fbsplash-emergence-1024x768
-rw-r--r--   1 root root 1267876 Nov 17  2004 fbsplash-emergence-1600x1200
-rw-r--r--   1 root root 2262456 Apr 12 23:19 fbsplash.tgz
drwxr-xr-x   2 root root    1024 Jul  7 10:53 grub
-rw-r--r--   1 root root  172826 Aug 18  2004 initrd-Emergance-1280x1024
-rw-r--r--   1 root root  101494 Jun 15  2004 initrd-gentoo-1280x1024
-rw-r--r--   1 root root  150334 Jun 15  2004 initrd-matrix-1280x1024
-rw-r--r--   1 root root 2171358 Aug 30 12:16 kernel-2.6.10-gentoo-r6-cpu
-rw-r--r--   1 root root   41895 Feb 27  2004 splash.initrd
lrwxr-xr-x   1 root root      24 Jul 21 19:55 vmlinuz ->
vmlinuz-2.6.10-gentoo-r6
-rw-r--r--   1 root root 2164025 Jul 21 19:55 vmlinuz-2.6.10-gentoo-r6

I don't see any mention of vmlinuz in my grub.conf file:

default=0
timeout=10
splashimage=(hd0,0)/boot/grub/splash.xpm.gz

title Gentoo Linux (2.6.10r6) [resume framebuffer splash 1600 CPU]
        root=(hd0,0)
        kernel=(hd0,0)/boot/kernel-2.6.10-gentoo-r6-cpu ro root=/dev/hda3
video=vesafb:ywrap,mtrr,1600x1200-16@60 splash=silent,theme:emergence
CONSOLE=/dev/tty1 hdb=ide-scsi resume=/dev/hda6 pmdisk=/dev/hda6
netdev=5,0xec80,eth0
        initrd (hd0,0)/boot/fbsplash-emergence-1600x1200


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Re: [gentoo-user] Do I need the vmlinuz symbolic link with Grub?

[Holly Bostick]

Daevid Vincent schreef:
> Somehow net-wireless/madwifi-driver has broken on me (0.1_pre20050420-r1),
> so I thought I'd recompile it. No luck. So I thought, maybe my kernel source
> was different than my actual kernel (2.6.10-gentoo-r6), so I ran: 
> "make bzImage modules modules_install"

OK, don't quite get this:

to see what kernel you're running do

uname -r

 uname -r
2.6.12-gentoo-r9

to see what kernel is linked to /usr/src/linux (which is the symlink
external modules will follow to determine what source to build against), do

la /usr/src/linux

la /usr/src/linux
lrwxrwxrwx  1 root root 23 aug 31 00:25 /usr/src/linux ->
linux-2.6.12-gentoo-r10

As you see, the kernel I am currently running is different from the
source that I downloaded earlier this evening and will compile tomorrow.
In less than 24 hours, both outputs will say the same thing.

I just don't get why people tend 'speculate' on stuff instead of just
checking. :) .

Also not quite sure why you're doing all those steps; it's like you're
running a 2.4 kernel or something.

For ages under 2.6, all that's needed is

make
make modules_install
make install or manual copy of the kernel to /boot

> 
> Copied and renamed the bzImage file over to /boot and all that jazz.
> 
> But I don't think I'm getting the right kernel as the date for my kernel is
> today, but my vmlinuz is older.
> 
> How is that symlink created? And how is the vmlinuz-2.6.10-gentoo-r6
> created? 

They are both created if you use 'make install' as the third step of
kernel compilation; the bzImage created by the 'make' command is copied
to /boot, renamed vmlinuz-whatever and symlinked to vmlinuz. Any
currently existing kernel's symlink is removed, and a new link is
created to vmlinuz.old. The same occurs for System.map and .config

The idea is that it simplifies GRUB configuration (you only have to say
the current kernel is vmlinuz and the previous one is vmlinuz.old. Any
yet older kernels can be added using the full name of
vmlinuz-kernel.version).

What happens if I rm that symlink or the file? Is my system
> unbootable?

Possibly, if you delete the kernel, and its the one you're using.
Nothing ever happens if you delete a symlink (it doesn't affect the
file), but of course any bootloader entries that refer to the symlink or
the deleted file will be invalid.

For reference, here's my grub.conf, and the contents of /boot:

       1 apr 27 18:52 boot -> .
      23 aug 28 19:18 config -> config-2.6.12-gentoo-r9
   60418 mrt 24 01:31 config-2.6.11.4-20a-default
   36162 jul  7 02:09 config-2.6.11-gentoo-r11
   36338 mei  5 00:52 config-2.6.11-gentoo-r6
   35926 jun 13 23:49 config-2.6.11-gentoo-r8
   32555 jul 24 02:08 config-2.6.12-gentoo-r6
   32009 aug 28 19:18 config-2.6.12-gentoo-r9
   32533 aug 28 18:19 config-2.6.12-gentoo-r9.old
      27 aug 28 19:18 config.old -> config-2.6.12-gentoo-r9.old
    1024 aug 23 19:57 grub
      27 apr 27 14:23 initrd -> initrd-2.6.11.4-20a-default
 1365529 apr 27 14:23 initrd-2.6.11.4-20a-default
       0 apr 29 00:47 .keep
   12288 apr 27 14:13 lost+found
  138240 apr 27 14:23 message
   68372 mrt 24 01:32 symvers-2.6.11.4-20a-i386-default.gz
      27 aug 28 19:18 System.map -> System.map-2.6.12-gentoo-r9
  708925 mrt 24 01:26 System.map-2.6.11.4-20a-default
 1015185 jul  7 02:09 System.map-2.6.11-gentoo-r11
 1022418 mei  5 00:52 System.map-2.6.11-gentoo-r6
  978467 jun 13 23:49 System.map-2.6.11-gentoo-r8
 1023832 jul 24 02:08 System.map-2.6.12-gentoo-r6
  972725 aug 28 19:18 System.map-2.6.12-gentoo-r9
  972876 aug 28 18:19 System.map-2.6.12-gentoo-r9.old
      31 aug 28 19:18 System.map.old -> System.map-2.6.12-gentoo-r9.old
    1024 apr 29 15:52 .Trash-root
      24 aug 28 19:18 vmlinuz -> vmlinuz-2.6.12-gentoo-r9
 1424645 mrt 24 01:26 vmlinuz-2.6.11.4-20a-default
 2231337 jul  7 02:09 vmlinuz-2.6.11-gentoo-r11
 2279794 mei  5 00:52 vmlinuz-2.6.11-gentoo-r6
 2132248 jun 13 23:49 vmlinuz-2.6.11-gentoo-r8
 2122433 jul 24 02:08 vmlinuz-2.6.12-gentoo-r6
 3540799 aug 28 19:18 vmlinuz-2.6.12-gentoo-r9
 3540532 aug 28 18:19 vmlinuz-2.6.12-gentoo-r9.old


I should probably get rid of the old 2.6.11 kernels, since I don't need
them for emergency backup anymore.

Anyway, when I compile 2.6.12-gentoo-r10 later today, 2.6.12-gentoo-r9
will be linked to vmlinuz.old (again), 2.6.12-gentoo-r10 will be linked
directly to vmlinuz, and any other kernels I want to put in the menu can
be linked directly by name:


splashimage=(hd0,1)/grub/grub-livecd2.xpm.gz
title Gentoo_current (2.6.12-gentoo-r9)
        root (hd0,1)
        kernel /vmlinuz ro quiet root=/dev/hda5
video=vesafb:ywrap,mtrr,1280x1024-32@60
splash=silent,fadein,theme:livecd-2005.1 CONSOLE=/dev/tty1
#       initrd (hd0,1)/fbsplash-emergence-2612-6

title Gentoo_prev (2.6.11-gentoo-r6)
        root (hd0,1)
        kernel /vmlinuz-2.6.11-gentoo-r6 ro root=/dev/hda5
video=vesafb:ywrap,pmipal,mtrr,1280x1024-32@60
splash=verbose,theme:emergence quiet CONSOLE=/dev/tty1
        initrd /fbsplash-emergence-2611-11

title SUSE LINUX 9.3
        root (hd0,1)
        kernel /vmlinuz-2.6.11.4-20a-default real_root=/dev/hda6
vga=0x317 selinux=0 splash=silent resume=/dev/hda6  showopts
        initrd /initrd-2.6.11.4-20a-default


The only reason that 2.6.11-r6 is not called with vmlinuz.old is because
I've been recompiling my kernel a lot the past couple of days, and there
wasn't much point in cleaning up my symlinks every time (though I will
do it before I compile 2.6.12-r10), so I just linked the entry directly
to the kernel rather than a symlink. The entry is obsolete anyway, so
I'll probably just delete it in the /boot cleanup.

HTH,
Holly
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Re: [gentoo-user] Do I need the vmlinuz symbolic link with Grub?

[Volker Armin Hemmann]

On Wednesday 31 August 2005 04:25, Daevid Vincent wrote:
> Somehow net-wireless/madwifi-driver has broken on me (0.1_pre20050420-r1),
> so I thought I'd recompile it. No luck. So I thought, maybe my kernel
> source was different than my actual kernel (2.6.10-gentoo-r6), so I ran:
> "make bzImage modules modules_install"
>
> Copied and renamed the bzImage file over to /boot and all that jazz.
>
> But I don't think I'm getting the right kernel as the date for my kernel is
> today, but my vmlinuz is older.
>
> How is that symlink created? And how is the vmlinuz-2.6.10-gentoo-r6
> created? What happens if I rm that symlink or the file? Is my system
> unbootable?
>

if you type 'make install' (very recommended) the vmlinuz-2.6.XX file is 
copied to /boot, alongside its corresponding config and system.map.
A 'vmlinuz'/'System.map' link is created that points to the latest installed 
kernel, and some '*.old' symlinks that point to the previous kernel version.

Can you safely remove all this symlinks?
Yes, of course.

But it is very convinient, to have vmlinuz and vmlinuz.old as boot options in 
grub.conf.
This way, you'll have nothing to do after an update, and the old kernel is 
always there as a safety net.

make all modules_install install and you have nothing to do (except 
mounting /boot).
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Re: [gentoo-user] Do I need the vmlinuz symbolic link with Grub?

[Nick Rout]

On Wed, 31 Aug 2005 04:56:50 +0200
Holly Bostick wrote:

> For ages under 2.6, all that's needed is
> 
> make
> make modules_install
> make install or manual copy of the kernel to /boot

yep, and if you forget what is what, there is always

make help



-- 
Nick Rout <nick@rout.co.nz>

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