root and boot floppy on ISC

[Marc Rossner]

In article <1991Apr11.171616.14088 at sci34hub.sci.com>, gary at sci34hub.sci.com (Gary Heston) writes:
> In article <538 at jahangir.UUCP> marc at jahangir.UUCP (Marc Rossner) writes:
> =In article <1991Apr3.203354.18641 at eci386.uucp>, woods at eci386.uucp (Greg A. Woods) writes:
> => In article <59 at talgras.UUCP> david at talgras.UUCP (David Hoopes) writes:
> => 	copy /etc/boot to track 0 (for 386/ix 1.0.6 anyway)
> =   ^^^^^^^^^^^^^^^^^^^^^^^^^
> =This is the part I can't figure out how to do.  Any hints?


Thanks to Gary and all others who emailed me to direct me to dd.  After some
exploration I think I can summarize the special issues involved with this
for ISC 2.2.

The problem is that the ISC2.2 kernel expects that if you are booting from
a floppy then your root file system is on a SECOND floppy (i.e. the "install"
floppy) on the device that DOES include sector 0 -- (eg /dev/dsk/f0q15dt).

If your file system were on the same disk as the boot and /unix, then it
would have to be on the device that does NOT include sector 0
(eg /dev/dsk/f0q15d) -- but since the kernel is trying to mount off the
other device it will choke in this case (i.e. "srmount -- not a valid root").

So it seems the solution (especially space-wise) is to use the 2-floopy
boot / root fs method.  I.e.

1.  Copy ISC's boot diskette.

2.  Mount your new diskette from /dev/dsk/f0q15d

3.  Replace /unix with your souped-up /unix (eg. I especially needed mine
    to contain the tape driver and Specialix port drivers).

4.  Unmount your new boot diskette

5.  Copy ISC's install diskette.

6.  Mount your new diskette from /dev/dsk/f0q15dt

7.  Get rid of all the "UI" stuff (menus from install procedure) and
    other stuff that is obviously extraneous.

8.  Put lots of good stuff on like ls, vi, ksh, cpio 

9.  change the INSTALL file to just contain "exec ksh" or something.

10. unmount your new root fs floppy.

The only problem with this system is that you can't do "ps" because there
is no /unix in your filesystem.  Any suggestions of a way to get around this
or a way to modify the kernel so it could boot and mount the same floppy if
you had enough room anyway?


Marc Rossner
jahangir!marc at uunet.uu.net