Default Kernel .config file

[Harrington, Todd]

-----Original Message-----
From: Harrington, Todd 
Sent: Friday, June 16, 2006 9:10 AM
To: 'Getting started with Red Hat Linux'
Subject: RE: Default Kernel .config file



Hi Rick,

Thanks for your answer. It was very helpful and answered 
several smaller questions I had. I have built my new kernel,
modules, modules_install, install. I then copied the /boot 
and the /lib directory back over to my boot server. 
I did not re-run mkinitrd because when I run the RHEL4 
Network Booting Service (system-config-netboot) it asks me to 
point to a kernel and I point to 
/diskless/i386/RHEL4-ES/root/ (where it finds the new kernel 
that I just installed) and it then builds an 
initrd.img for me and sticks the initrd.img and new kernel
into /tftpboot/linux-install/IMAGENAME
There sizes look very good.

So my problem NOW is that when my diskless client boots the 
kernel loads and then I get this from initrd:

RAMDISK: Compress image found at block 0
-
-
Running /disklessrc
Mounting /proc
disklessrc: Line 71: /sbin/uniq: Permission denied
disklessrc: Line 66: /sbin/sed: Permission denied
disklessrc: Line 68: /sbin/uname: Permission denied
disklessrc: Line 68: /sbin/grep: Permission denied
(several more lines of this)
Loaded nfs OK
Mounting /
disklessrc: line 163: /bin/cat: Permission denied
Running dhclient
bash-3.00#

At this shell all commands are permission denied.

This is so important that I get by this today.
Do you know what my problem is? 

Thanks,
Todd

-----Original Message-----
From: redhat-install-list-bounces at redhat.com
[mailto:redhat-install-list-bounces at redhat.com]On Behalf Of Rick Stevens
Sent: Thursday, June 15, 2006 4:51 PM
To: Getting started with Red Hat Linux
Subject: Re: Default Kernel .config file


On Thu, 2006-06-15 at 15:08 -0500, Harrington, Todd wrote:
> Hello,
> 
> I am installing RHEL4 ES on a "client" computer. I do a fresh load to a local hard drive on the "client" with the goal of eventually making this node a "diskless client" that will boot via PXE.. 
> I use the Netboot GUI on my Linux "server" (another machine) that comes with RedHat and it pulls the image and kernel from my hard drive on my "client" and I can now PXE boot my client from the server. I am actually now booting the default kernel that was installed on the hard drive of my "client". Life is good. 
> 
> My problem is that I want to reconfigure the kernel on my client and when I do, the default .config files (in the "configs" directory or the Config-xxx file in the /boot directory) do not contain the same settings as are in my original kernel and my new kernel does not boot across the network. I have been pulling my hair out trying to get my new kernel to boot. How can I get the default .config settings for the kernel that was initially installed to my local hard drive? I read about "extract_ikconfig" and /proc/config that allow you to pull the .config info from a kernel but you have to have that support in the kernel in the first place. It does not appear the initial RedHat install included this in the kernel.

In the future, please format your messages as plain text, 72 characters
per line.  Not all mail readers deal with long lines well.

Now, to your problem...

When RHEL installs, the config file that matches the kernel that was
installed is the "/boot/config-`uname -r`" file.  The only difference
between that config file and the actual kernel is that the kernel was
built with the "CONFIG_DEBUG_INFO" option (in the "Kernel->Hacking"
section) turned off, which creates modules that don't have full debug
info in them and are therefore smaller in size.

Also note that the default kernels put all of the network, SCSI and
non-ext2 filesystem drivers in the initrd image file.  If you
reconfigure the kernel, you have to rebuild the initrd image.  That's
done by:

	# cd /boot
	# mkinitrd -f -v initrd-whatever.img whatever

replacing "whatever" with the kernel version number you're working with.
Note that both the kernel AND the initrd image must be on your boot
server or the kernel won't be able to find the drivers it needs.

Now, you CAN reconfigure the kernel and build the necessary network
and filesystem drivers into the kernel and remove the need for an initrd
image completely, but if you change the hardware (say, swap out an
Intel e1000 card for an Intel e100 card), you won't be able to boot from
the network again since the driver for the card won't be present.

My quicky document on building kernels and such can be found here:

	http://www.rhil.net/docs/kernelbuild-26.html

----------------------------------------------------------------------
- Rick Stevens, Senior Systems Engineer     rstevens at vitalstream.com -
- VitalStream, Inc.                       http://www.vitalstream.com -
-                                                                    -
-               The Theory of Rapitivity: E=MC Hammer                -
-                                  -- Glenn Marcus (via TopFive.com) -
----------------------------------------------------------------------

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Hi, I am all set now. I was required to copy the file busybox.anaconda 
to my client's /sbin directory and when I did the permissions did not 
have execute permissions on it. I did a chmod to busybox.anaconda and now
I can boot! Thank you to this mailing list.

- Todd