verify kernel compile macro in running linux

How to check whether a kernel compile macro is enabled on a running linux machine?

root@babu-VirtualBox:~/tools/stk_corruption/stk_overflow_lkm# grep OVERFLOW /boot/config-3.13.5
CONFIG_HAVE_DEBUG_STACKOVERFLOW=y
# CONFIG_DEBUG_STACKOVERFLOW is not set
root@babu-VirtualBox:~/tools/stk_corruption/stk_overflow_lkm#

How to edit boot options during linux booting?

The following steps worked for me in a Virtualbox Ubuntu VM:

• During the boot up menu, select the kernel version you want to boot with: 

                        

                        

• Press 'e' to enable editing of this line:

                        

• Go to "linux" bootline & add the boot options. I am adding slub_debug option in my screen:

                        

                        

• Do these boot options get retained across reboot?

          No. 

How to - Linux Kernel Compilation in Ubuntu VM/VirtualBox

I recently compiled linux kernel in a Virtualbox VM. Here are the steps I used to compile a custom linux kernel. These steps worked for me in Ubuntu 13.10 distribution.


Check the linux version of your VM:

babu@babu-VirtualBox:~$ uname -a

Linux babu-VirtualBox 3.11.0-12-generic #19-Ubuntu SMP Wed Oct 9 16:12:00 UTC 2013 i686 i686 i686 GNU/Linux

babu@babu-VirtualBox:~$ 

Switch to root mode:

babu@babu-VirtualBox:~$ sudo -s

[sudo] password for babu: 

root@babu-VirtualBox:~#

Download the linux sources for the matching version to /usr/src:

root@babu-VirtualBox:~# cd /usr/src

root@babu-VirtualBox:/usr/src# 

root@babu-VirtualBox:/usr/src# ls

linux-headers-3.11.0-12          vboxguest-4.3.6

linux-headers-3.11.0-12-generic

root@babu-VirtualBox:/usr/src# wget http://www.kernel.org/pub/linux/kernel/v3.x/linux-3.11-tar.bz2

.

.

root@babu-VirtualBox:/usr/src#

In my case, I didn't have tarball for 3.11.0 at http://www.kernel.org/pub/linux/kernel/v3x/. So, I got linux-3.11.tar.bz2 instead:

root@babu-VirtualBox:/usr/src# ls 

linux-headers-3.11.0-12          vboxguest-4.3.6

linux-3.11.tar.bz2  linux-headers-3.11.0-12-generic

root@babu-VirtualBox:/usr/src# 

Extract the source to /usr/src:

root@babu-VirtualBox:/usr/src# tar -xvf linux-3.11.tar.bz2 -C .

.

.

root@babu-VirtualBox:/usr/src# ls

linux-3.11          linux-headers-3.11.0-12          vboxguest-4.3.6

linux-3.11.tar.bz2  linux-headers-3.11.0-12-generic

root@babu-VirtualBox:/usr/src# 

Install compilation tools necessary:

apt-get update

apt-get install gcc

apt-get install make

apt-get install ncurses-*

Select the kernel configuration options you need:

root@babu-VirtualBox:/usr/src# cd linux-3.11/

root@babu-VirtualBox:/usr/src/linux-3.11# make menuconfig

Compile & Install the Kernel:

root@babu-VirtualBox:/usr/src/linux-3.11# make     <-- This step took approximately 2 hours on my dual core VM.

.

.

root@babu-VirtualBox:/usr/src/linux-3.11#  make modules <-- This step took approximately 2 minutes.

.

.

root@babu-VirtualBox:/usr/src/linux-3.11# make modules_install  <-- This step took approximately 10 minutes.

.

.

root@babu-VirtualBox:/usr/src/linux-3.11# make install

.

.

root@babu-VirtualBox:/usr/src/linux-3.11#

Initrd creation & GRUB modification:

I didn't have to create initrd image or a grub entry. An initrd image was already generated in /boot directory & my new image was already in /boot/grub/grub.cfg. I guess grub2 made this step automatic?

Reboot:

/sbin/reboot

Select the new custom created kernel during bootup:

Before the VM boots up, hold the shift key to get the bootloader options list. Then, select "Advanced Options for Ubuntu":

                    

Then in the next menu, select your custom kernel:

                    

Verify that your VM indeed is running the new custom kernel:

babu@babu-VirtualBox:~$ uname -a

Linux babu-VirtualBox 3.11.0 #3 SMP Fri Feb 14 10:54:07 PST 2014 i686 i686 i686 GNU/Linux

babu@babu-VirtualBox:~$ 

Thats it. Hope this helps.