[Unix-jun72] cold boot tape

[Unix-jun72] cold boot tape

[Tim Newsham]

I wrote a utility for building a cold boot tape and included it in the 
tools directory.  Its not yet tested so its possible I got the format 
wrong... its based on my reading of init at the end of u0.s.

It seems like the permissions in the s2.tar.gz file from the
1972_stuff reflect the original 1ed permission bits (at least the
low order bits do) so this makes restoring the original permissions
fairly easy.  Unfortunately the tar doesn't preserve the original
uids.  The included "Readme" does have the original uids, so its
possible to recreate the proper uids by hand.  If you do so,
my mktape utility should write out the proper uid and mode values.

The use is straightforward:

     cd /your/s2/directory
     /path/to/mktape.py bin/* etc/*

and you'll get a "tape" file out.  I believe you just need the
stuf in bin and etc.  The stuff from usr should probably go on
the rk03 disk after cold boot.

Tim Newsham
http://www.thenewsh.com/~newsham/

[Unix-jun72] cold boot tape

[Tim Newsham]

> I wrote a utility for building a cold boot tape and included it in the
> tools directory.  Its not yet tested so its possible I got the format
> wrong... its based on my reading of init at the end of u0.s.

It occurs to me that the tape is probably meant to be bootable.
The init program seeks to the 65th block to start booting, so blocks
0 through 64 can be used to hold a bootable kernel image or two.
I'm guessing we could make a tape as:

     blocks 0-31  - the "cold" kernel
     blocks 32-64 - the real kernel
     blocks 65-   - the contents of /bin and /etc

boot the cold kernel from tape, have it write out a primordeal root
file system on rf0.  Boot the real kernel from tape, have it
run the /etc/init that the cold kernel put onto rf0 which reads
files from blocks 65 onwards on the tape.  Finally reboot the real
kernel from tape again and be in a real system.

By the way, I made some tape images from the s2 binaries (just /etc
and /bin, /usr is probably meant to go onto rk0):

    http://www.thenewsh.com/%7Enewsham/unix_jun72/tape
        - the raw tape bits with the first 65 blocks empty
    http://www.thenewsh.com/%7Enewsham/unix_jun72/tape.tc
        - a simh format tape of the above bits

the tape image isnt tested yet.  It should hopefully have the right
uids and file modes for first ed.

Tim Newsham
http://www.thenewsh.com/~newsham/