[comp.os.vms] Bug in v4.x images running on v5.0

fjb@metaware.metaware.com (Fred Bourgeois) (11/20/89)

    We are running VMS v5.0 and are having the following problem:

    We have customers who are using v4.x and v5.x.  We only have one
VMS system (running v5.0).  The problem is that we need to create
executable images that run under both v4.x and v5.x.

    We still have the VMS v4.7 libraries (.olb files, and shareable
.exe files).  We do not have a backup of VMS v4.7 (so we cannot go
back to an earlier version of VMS).

    Although the answer may at first seem trivial, it is not.  I know
about "$ link /nosyslib/nouser", and I am using the private copies of
the v4.7 object libraries and shareable images in my options file
(Note that the "/shareable=copy" option no longer exists).  I have
successfully created v4.7 executables on our v5.0 system in the past.

    One of our customers recently reported a bug in which their
cross-compiler gives a stack dump (access violation, specific instr:
"BISL2 (R10)+, (R11)+", with R10 == 0 (the source of the problem)).
They are running a v4.7 image on their v5.1 system.  I can produce the
same problem on our v5.0 system, but when I use the v5.0 image, the
problem disappears (i.e.  R10 != 0 at this point in the image, as is
expected).

    Does anyone know
	a)  Why this happens (I suspect a problem in v4.7 alloc(),
		or its interface to v5.x librtl).
	b)  How do I avoid this problem (i.e. how do I link v4.7
		images on v5.0 that will also run under v5.x)

Further information:
    The product in question is a cross-compiler which runs on a large
number of platforms.  Compiling the same code [that produces this bug on
VMS] causes no problems on any other platform.

	     Colorless Green Ideas Sleep Furiously, and so do I.
------------------------------------------------------------------------------
Fred Bourgeois       [Insert standard disclaimers here]         MetaWare, Inc.
metaware!fjb@uunet.uu.net               |                 2161 Delaware Avenue
...!{acad,amdcad}!metaware!fjb          |            Santa Cruz, CA 95060-2806
------------------------------------------------------------------------------