It's not common to need them, perhaps, but it's still useful if you don't want to recompile your kernel just to add on-boot support for various devices. Slackware's 'mkinitrd' tool is one example of this sort of approach; you can add various modules (like for your root filesystem, keyboard, etc.) by adding to the $MODULE_LIST variable defined in '/etc/mkinitrd.conf' or by running 'mkinitrd -k $MODULES'.
You can of course accomplish similar things by just recompiling the kernel (which Slackware makes very easy to do), but if you still need to use 'mkinitrd' anyway (perhaps because you're using LVM or softraid or LUKS), it's often more convenient to just throw in the modules you need while you're at it.
You can of course accomplish similar things by just recompiling the kernel (which Slackware makes very easy to do), but if you still need to use 'mkinitrd' anyway (perhaps because you're using LVM or softraid or LUKS), it's often more convenient to just throw in the modules you need while you're at it.