This really works! I did it and had no problems. [bjcarter@gte.net]

Having said that, here is a procedure for upgrading DR2.1 to DR3 without going through the "trouble" of backing up your files and reformatting your hard drive. It's been a while since I did this, but I believe I have documented all the steps necessary. This assumes you installed shared library support in DR2.1update4. [ddkilzer@earthlink.net]

  1. Boot into DR2.1 and update to DR3 kernels.  The latest release with 
     source is DR3alpha5, or WIP 980421.  Read the README file, and then 
     update your bootstrap.conf, default_pager, vmlinux and "Mach Kernel" 
     files.

       ftp://ftp.mklinux.apple.com//pub/wip/980421/README
       ftp://ftp.mklinux.apple.com//pub/wip/980421/

     MAKE SURE TO SAVE COPIES OF YOUR OLD FILES!  In case MkLinux doesn't
     work when you reboot, you will need to move the old files back into 
     place.

  2. Boot into Mac OS.  Fix lilo.conf in your System Folder:Preferences 
     folder under Mac OS.  (You can use the MkLinux control panel for this 
     if you have it installed.  Otherwise run SimpleText yourself to edit 
     the file.)

     Beginning with WIP-971126, SCSI drive ordering became dynamic on boot.
     SCSI is scanned from bus 0 to bus 1, from id 0 to id 7.  Drives found 
     during the scan are named /dev/sda, /dev/sdb, /dev/sdc, /dev/sdd, etc.

     Tape drives and CD-ROM drives are assigned to different devices.  Zip,
     Jaz, Syquest, and other removable media *are* included in this
     lettering.  For example, if you have a Zip drive "between" two hard 
     drives, your second hard drive will be /dev/sdb (if the Zip drive is 
     not present) or /dev/sdc (if the Zip drive is present).  

     For more (confusing) info, see the 971126 README.

       ftp://ftp.mklinux.apple.com//pub/wip/971126/README

     For people with single SCSI hard drive, you will use /dev/sda.  For 
     everyone else, YMMV.

  3. Reboot to try the new DR3.  If something went wrong, use LinuxDisks
     (and pay the shareware fee) to move the old files back into place.  

  4. Upgrade to the latest packages below.  It is important that you do
     this *after* upgrading to the DR3 kernels.  There is a bug/conflict
     between the DR3 packages and the DR2.1 kernels that cause shared
     libraries to be written to and thus corrupted!

     NOTE 1: If you don't do any compiling, then the binutils and the egcs 
     packages are not strictly required, but I strongly recommend you 
     upgrade them anyway.  The egcs packages replace gcc packages (egcs
     has better PowerPC support), and you will want to remove your gcc
     packages before installing the egcs ones with "rpm -e packagename".

     NOTE 2: Whenever installing new glibc packages, it is recommended that
     one should perform the following lobotomy:

        rm -rf /usr/include/*

     I was not brave enough to do this, and have left /usr/include/ alone
     for the most part.  The only problem I've run into was some outdated
     header files in /usr/include/bsd/.  After determining which ones were
     not part of any package, I removed them and had no further problems.

     You may want to simply move the old "/usr/include/" directory out of
     the way (if you have the space), and then install the new glibc
     packages.

        mv /usr/include /usr/include-old
        mkdir /usr/include

     NOTE 3: When upgrading ldconfig, use the "--nodeps" flag with RPM.

     NOTE 4: If you're getting false dependencies on "/bin/sh" when 
     installing RPMS, you need to upgrade to the latest version of RPM to 
     fix this.

     The latest packages (recommended) are:

        binutils-2.9.1-1a.ppc.rpm
        egcs-1.0-2e.ppc.rpm
        egcs-as-gcc-1.0-2e.ppc.rpm
        egcs-c++-1.0-2e.ppc.rpm
        egcs-g77-1.0-2e.ppc.rpm
        egcs-objc-1.0-2e.ppc.rpm
        glibc-0.961212-1g.ppc.rpm
        glibc-devel-0.961212-1g.ppc.rpm
        glibc-static-0.961212-1g.ppc.rpm
        ldconfig-1.9.5-2a.ppc.rpm
        libg++-2.8.1.980306-1c.ppc.rpm
        libg++-devel-2.8.1.980306-1c.ppc.rpm

     These are available from either site:

       ftp://ftp.mklinux.apple.com/pub/DR3/RedHat/RPMS/
       ftp://ftp.linuxppc.org/linuxppc/redhat/RPMS/ppc/

  5. Update other RPM packages as needed.  I recommend upgrading the X11
     packages initially.  IMPORTANT: See the note about updating X11 RPMs!

        Why does RPM complain when installing new X11 RPMS in MkLinux DR2.1?

     NOTE 1: Many files and programs installed under DR2.1 did NOT belong
     to any RPM package.  Download and install the new RPMS as needed.

     NOTE 2: Again, if you're getting false dependencies on "/bin/sh" when 
     installing RPMS, you need to upgrade to the latest version of RPM to 
     fix this.