Slackware's initrd.img changed from gzip encryption to lz. The old method of
zcat /boot/initrd-$(uname -r).img | cpio -idmv
to extract slackware's boot initrd, has become:
xz -dc < /boot/initrd-$(uname -r).img | cpio -idmv
One of the reasons I need to know how to extract a Slackware initrd is to chroot into it. I chroot into the Slackware initrd and use it to install Slackware on remote servers.