Running Lites on Linux Hosts

This Lites release cannot yet be fully hosted by a Linux system. So far, the following things work:

• ext2fs support is there, without which this whole thing would be pointless.

• support for QMAGIC binaries was added. QMAGIC replaced ZMAGIC as Linux's standard format about half a year ago. ELF support for Linux still needs to be added.

• Support for Linux mount and reboot was added.

• Support for Linux /dev conversion was added. The motivation is that Linux uses Minix device numbers, whereas Lites uses *BSD numbers. Thus, if we don't want to have different servers (with different conf.c files), Linux and Lites cannot share a common /dev directory.

  This is currently done by using the AFS @sys hack recognized by Lites. To configure your Linux root filesystem to use either Linux or Lites do the following (as root):

    mkdir /i386_linux
    ln -s i386_linux @sys
    mv dev i386_linux/dev
    ln -s @sys/dev dev
  

  These commands enable Linux to continue working, with /dev/xxx translating to /i386_linux/dev/xxx. The following sets up a device directory for Lites (you will need a copy of the NetBSD MAKEDEV script to do this):

    mkdir /i386_lites /i386_lites/dev
    cp MAKEDEV.NetBSD /i386_lites/dev/MAKEDEV
    cd /i386_lites/dev; ./MAKEDEV all
    mknod time c 25 0 ; mknod timezone c 26 0
  

  The time and timezone special files are used by the Lites emulator. You will also need to create Linux aliases for the NetBSD special files, for example:

    ln -s wd0a hda1
    ln -s wd0e hda2
    ln -s console tty1
  

  Thus, when running a Linux binary under Lites, /dev/hda1 will eventually translate to /i386_lites/dev/wd0a, which has the right (*BSD) device number.

  This seems to be a major hack. We're open for suggestions.

• If the above was configured, you should be able to get a shell by using the following script as /mach_servers/mach_init:

  #!/bin/sh
  exec /sbin/agetty 38400 console
  

  Note that the console is not properly set up, you need to type ^J instead of Return. Other than that, you should be able to log on and issue commands.

• using normal /sbin/init fails. Due to some problems related to signal handling, the kernel will usually panic after 45 sec.
• Linux /bin/ls. Presumably that's a bug in the emulator. Note that Linux /bin/ls works on a Lites/NetBSD system and that NetBSD /bin/ls works on Lites/Linux, just Linux /bin/ls doesn't work on Lites/Linux.

• mounting wd0e on /usr (our tested system has a separate /usr partition) It says ``device not configured''. Maybe Mach doesn't recognize the second Linux partition for some reason?

• when the server comes up, it has / mounted read-only. Remounting it read-write is not as simple as it may seem, due to a number of idiosyncrasies in *BSD/mount, Linux/mount, and the Lites mount implementation. This is a long story nobody wants to hear.

  ONLY the following command works:

    /sbin/mount -wn -t ext2 -o remount /dev/hda1 /
  

  [because it says do not try to write /etc/mtab (-n), do not probe for fstype (-t ext2), set MS_REMOUNT (-o remount) do not read /etc/mtab for the special file (/dev/hda1)]

  Another problem is that Linux's mount writes canonicalized filenames in /etc/mtab. Unfortunately, the Linux mount executed in rc.d/rc.S reads from /etc/mtab...