*BSD News Article 43761


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From: erandall@reo.dec.com (Ed Randall)
Newsgroups: comp.unix.bsd.freebsd.misc
Subject: mmap() problem [940412-SNAP, pdksh]
Date: 9 May 1995 11:11:59 GMT
Organization: Digital Equipment Corporation, Palo Alto, CA, USA
Lines: 37
Message-ID: <3onilv$5jb$1@usenet.pa.dec.com>
NNTP-Posting-Host: cics03.reo.dec.com
X-Newsreader: TIN [version 1.2 PL2]


Over the weekend I finally erased Linux and began installing FreeBSD
from the 950412-SNAP distribution.  Having struggled through a few
initial partitioning problems (don't do too many things in "disklabel",
it crashes !) I finally got it all up & running.

Problem #1 - all my old scripts don't work, 'cos I always write 'em
in ksh;  So I got the pdksh-??.13 (the latest anyway) distribution,
and started to build it.

Problem #2 - During the "configure" script, it hangs when scanning for
"mmap()".  A "kill -9" of the parent shell of the "configure" process
will bring back a prompt ... but the "configure" process is still there.
Any attempt to "ls" the directory it was in, or "cat" any files in that
directory, result in another hang.  Oh dear !

I investigated this in more depth (adding printf's to the .c file used 
by "configure" for testing "mmap()") and it seems that the hang occurs
in the read() performed just after the call to "mmap()".

"Oh well, it's obviously broken" I thought, and hacked "configure" so 
that "HAVE_MMAP" doesn't get defined, and the problematical test is skipped.
I now have a working "ksh", all seems well.

But what of the miscreant "mmap()" ?  Is this a known bug, or should it
work ?  Has anybody else had similar problems when running the "configure"
scripts provided with most ports ?

Any help / pointers / ideas gratefully accepted !

Ed

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Ed Randall           Digital Equipment Co.Ltd., Worton Grange, Reading
DECnet : RDGENG::RANDALL                   Internal phone : 7-830-4712 
Internet : erandall@muffit.reo.dec.com       Telephone: (01734) 204712
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