[TUHS] 211bsd: kernel panic after a 'here document' in tcsh

Walter F.J. Mueller w.f.j.mueller at retro11.de
Thu Jun 8 06:14:07 AEST 2017


a few remarks on the feedback on the kernel panic after a 'here document' in tcsh.

To Michael Kjörling question:
 > I'm curious whether the same thing happens if you try that in some
 > other shell? (Not sure how widely here documents were supported back
 > then, but I'm asking anyway.)
And Johnny Billquist remark
 > Not sure if any of the other shells have this.

'here documents' are available and work fine in sh and csh.
And are in fact used, examples

   /usr/adm/daily     (a /bin/sh script)
     su uucp << EOF

   /usr/crash/why     (a /bin/csh script)
     adb -k {unix,core}.$1 << 'EOF'

To Michael Kjörling remark
 > The PC value in the panic report ("pc 161324") strikes me as high
and Johnny Billquist remark
 > This is in kernel mode, and that is in the I/O page.

211bsd uses split I/D space and uses all 64 kB I space for code.
The top 8 kB are in fact  the overlay area, and the crash happened
in overlay 4 (as indicated by ov 4). With a simple

   nm /unix | sort | grep " 4"

one gets

   161254 t ~psignal 4
   162302 t ~issignal 4

so the crash is just 050 bytes after the entry point of psignal. So the
PC address is fine and not the problem. For psignal look at


the crash must be one of the first lines. psignal is an internal kernel
function, called from


and has nothing to do with the libc function psignal


To Johnny Billquist remark
 > Could you (Walter) try the latest version of 2.11BSD and see if you
 > still get that crash?

very interesting that you see a core dump of tcsh rather a kernel panic.

Whatever tcsh does, it should not lead to a kernel panic, and if it does,
it is primarily a bug of the kernel. It looks like there are two issues,
one in tcsh, and one in the kernel. I've a hunch were this might come from,
but that will take a weekend or two to check on.

		With best regards,  Walter

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