An initrd allows to use the smaller generic kernel instead of the huge kernel

slackware/README.initrd

On a locally available (with phsical access to keyboard and display) machine with ext4 on / the following should suffice:

cp -a /boot /boot.bak
cd /boot
mkinitrd -c -k 3.14.18-smp -m ext4 # use your kernel version here!

Now Edit lilo.conf :

image = /boot/vmlinuz -> image = /boot/vmlinuz-generic-smp
add initrd = /boot/initrd.gz

There is no need to update symlinks in /boot if you made sure, your lilo.conf point to the right generic kernel verion

An finally run lilo

According to linuxquestions the virtio kernel modules are necessary for KVM in the initrd.gz. A simple call like described in README.initrd, eg mkinitrd -c -k 3.10.17 -m ext4 will not include the virtio modules (tested) ⇒ Use /usr/share/mkinitrd/mkinitrd_command_generator.sh

In http://docs.slackware.com/howtos:slackware_admin:systemupgrade mkinitrd_command_generator.sh is mentioned as well

cp -a /boot /boot.bak 
cd /boot 
/usr/share/mkinitrd/mkinitrd_command_generator.sh > generated_mkinitrd_command
chmod +x generated_mkinitrd_command 
./generated_mkinitrd_command 
chmod -x generated_mkinitrd_command 
# Compare generic kernel version number in /boot with version number in lilo.conf! 
lilo 
reboot

To use the recommended generic instead of the huge kernel you have to build an initrd. This section is based on slackware-13.1/README.initrd

Make a copy of /boot dir to be on the save side: cp -a /boot /boot.org

Create the initial ramdisk filesystem /boot/initrd.gz with

mkinitrd -c -k 2.6.33.4-smp -m ext3 -f ext3 -r /dev/sda2

In this example we have an ext3 root „/“ partition on /dev/sda2 (see ls -al /dev/root) for a kernel of version 2.6.33.4-smp (See uname -r).
Or

mkinitrd -c -k 2.6.33.4-smp -m reiserfs

for Reiserfs, or

mkinitrd -c -k 2.6.33.4-smp -m ext4 -f ext4 -r /dev/sda2

for ext4 on /dev/sda2

It is not necessary to change the symlinks in /boot

Add a new image-section at the beginning of the image sections to /etc/lilo.config:

image = /boot/vmlinuz-generic-smp-2.6.33.4-smp
  initrd  = /boot/initrd.gz
  root= /dev/sda2
  label = LinuxGeneric
  read-only

Run lilo and restart.