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From: jnc@mercury.lcs.mit.edu (Noel Chiappa)
To: tuhs@tuhs.org
Cc: jnc@mercury.lcs.mit.edu
Subject: Re: [TUHS] Fwd: Choice of Unix for 11/03 and 11/23+ Systems
Date: Tue,  6 Oct 2020 10:46:48 -0400 (EDT)	[thread overview]
Message-ID: <20201006144648.773F918C0C4@mercury.lcs.mit.edu> (raw)

    >> Then on to trying to find out why MiniUnix crashes whenever I try and do
    >> anything significant.

    > I decided I wasn't up to tackling that, so instead I did all the edits
    > to produce an LSI-11 version of MX. ... I need to go
    > back and put conditional assembly flags in mch.s so there's only one
    > source file for both kinds of system. Doesn't boot, though.

So this has turned into a big swamp.

I went back and did the conditionals, and I can turn off the -11/03 flag and
produce the identical binary to the original mch.o file. -11/05 systems built
with that still won't boot, though!

So I had made some minor changes elsewhere in the system; e.g. a few files
(bio.c, clock.c, slp.c, and tty.c) refer the the PS explicitly (a no-no in the
-11/03) so I changed them all to call getps() and putps(), and added /05
versions of those to mch.s; so I backed them out, and re-built the system
using the original binaries of those; _still_ won't boot.

I then tried the original 'rkmx', and that _does_ boot; so there's no
mysterious damage to the file system. But now I'm deeply puzzled, since the
new system (which won't boot) should be basically identical (OK, not
bit-for-bit identical, but close).


So then I started trying to see why the new /05 system won't boot; the exec()
call in process 1 that starts /etc/init seems to be failing. Digging into
that, the call to namei() (in sys1$exec()) seems to be failing? Huh? The
file-system is OK (see above)?

So I'm trying to work out how that is happening. Which is non-trivial;
namei() is pretty convoluted. I can deal with the fact that there are two
nested loops using goto's (not the best form, but I can grok it), but then I
run into things like this:

     for(cp = &u.u_dbuf[0]; cp < &u.u_dbuf[DIRSIZ]; cp++)
	 if(*cp != cp[u.u_dent.u_name - u.u_dbuf])

Check out that second line! (And Heinz didn't touch it; this copy is from the
V6 source.) I'm not sure I 100% grok it, but I think I get roughly what it's
doing: 'cp' seems to be a (moving) pointer into the filename being matched,
and the term inside the []'s seems to be an offset from there into the copy of
the current directory entry in the 'u' structure. (Which is a constant, it
doesn't need to be recomputed each time around the loop, though.) It seems to
check most of the (wrong) directory entries OK, but then inexplicably (to me)
fails.


At this point I'm getting a bad feeling that there could be a sim issue; that
could also explain the problem I'm seeing with the crashes, when trying to run
'cc' under the as-distributed -11/05 version.`

I'm not a SIMH user, though (I'm an Ersatz-11 person); is there anyone who is,
who'd like to play with MiniUnix with me?

	Noel

             reply	other threads:[~2020-10-06 15:11 UTC|newest]

Thread overview: 70+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-10-06 14:46 Noel Chiappa [this message]
2020-10-06 16:22 ` jay-tuhs9915
  -- strict thread matches above, loose matches on Subject: below --
2021-02-03  1:25 Noel Chiappa
2020-10-18 21:36 Norman Wilson
2020-10-12 22:43 Noel Chiappa
2020-10-12 19:27 Noel Chiappa
2020-10-10 23:29 Noel Chiappa
2020-10-11  2:30 ` Jay Logue
2020-10-11 23:24 ` Paul Riley
2020-10-12  0:53   ` Dave Horsfall
2020-10-12  1:56     ` Warner Losh
2020-10-12  2:09       ` Andrew Warkentin
2020-10-12 16:57       ` Arthur Krewat
2020-10-18 20:42     ` Michael Huff
2020-10-08 23:49 Noel Chiappa
2020-10-08 16:06 Noel Chiappa
2020-10-06 23:08 Noel Chiappa
2020-10-07  5:24 ` Jay Logue
2020-10-06 20:34 Noel Chiappa
2020-10-06 19:34 Noel Chiappa
2020-10-06 19:04 Noel Chiappa
2020-10-02  0:39 Noel Chiappa
2020-10-01 12:51 Noel Chiappa
2020-10-02  0:23 ` Paul Riley
2020-09-30 23:16 Noel Chiappa
2020-09-30 18:51 Noel Chiappa
2020-09-30 17:58 Noel Chiappa
2020-09-28 23:21 Noel Chiappa
2020-09-30  1:50 ` Paul Riley
2020-09-27 21:07 Noel Chiappa
2020-09-27 21:12 ` Warner Losh
2020-09-28  0:22   ` Pete Turnbull
2020-09-27 20:50 Noel Chiappa
2020-09-29 13:20 ` Paul Riley
2020-09-25 22:08 Noel Chiappa
2020-09-26 14:52 ` John Foust
2020-09-28  0:03 ` Paul Riley
2020-09-28  0:06   ` Paul Riley
2020-09-24 18:56 Noel Chiappa
2020-09-24 13:04 Noel Chiappa
2020-09-24 18:24 ` John Cowan
2020-09-24 11:02 Paul Ruizendaal
2021-02-03  0:12 ` Greg A. Woods
2020-09-24  1:28 Noel Chiappa
2020-09-23 23:14 Noel Chiappa
2020-09-24  1:09 ` John Foust
2020-09-22 21:51 John Foust
2020-09-22 21:36 Noel Chiappa
2020-09-22 21:46 ` Warner Losh
2020-09-22 21:49 ` John Foust
2020-09-22 15:59 Noel Chiappa
2021-02-03  0:07 ` Greg A. Woods
2020-09-22  0:47 Noel Chiappa
2020-09-21 19:37 Noel Chiappa
2020-09-21 23:16 ` devin davison
2020-09-21 18:13 Noel Chiappa
2020-09-21 17:59 Noel Chiappa
2020-09-21 18:18 ` Arthur Krewat
2020-09-20 13:12 Noel Chiappa
2020-09-19 15:28 Noel Chiappa
2020-09-21 10:26 ` Paul Riley
2021-01-24 16:07 ` Tom Ivar Helbekkmo via TUHS
2021-01-25  4:58   ` Gregg Levine
2021-01-25  8:21     ` Tom Ivar Helbekkmo via TUHS
     [not found] <CAD05_j1bc6DDRtfPkd4QVeWXjwSp73bty46D=2ATozUbHThBWw@mail.gmail.com>
2020-09-19  3:22 ` Paul Riley
2020-09-19 14:20   ` Heinz Lycklama
2020-09-21 13:54     ` Paul Riley
2020-09-21 15:30       ` Heinz Lycklama
2020-09-21 23:27   ` Henry Bent
     [not found]     ` <4C35E6D2-8ABD-4DC2-BB2F-F15FA5BF30DD@icloud.com>
2020-09-22  0:22       ` Henry Bent

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