Here are some notes for using a development-kernel 2.1.x:
- base/kernel21.tgz contains the newest 2.1.x-kernel (2.1.105 at the moment)
  and you can add /boot/zImage-2.1 to your lilo.conf to start it
- if you also install develop/linc21.tgz, you get the new kernel include files
  in /usr/include/{linux-2.1,asm-i386-2.1,asm-generic-2.1,scsi-2.1}
  you can use "/usr/sbin/usekernelinc 2.0" and "/usr/sbin/usekernelinc 2.1"
  to switch between the 2.0 and 2.1 kernel header files
- you have to recompile "net-tools" to use newer features like the
  "txqueuelen" option for ifconfig.
- you can use the newer kernel nfsd (/etc/rc.d/init.d/knfs) or the old
  user level nfs-server
- you should recompile the isdn utilities
- ipfwadm is replaced by ipchains, but there is a "ipfwadm-wrapper"-script
  that does most conversions automatically
- /usr/sbin/tcpdump-2.1 should work for kernel 2.1.x and higher