shareable images

[Steve Summit]

Has anyone attacked the problem of generating shareable images
to run under vms?  The assembler (in this case, Eunice's vmsas)
has to provide the linker (in this case, vms link) with
information about which psects are position-independent, which
data segments can be shared, etc.  It looks like it could be a
mess to figure out.  I'm not sure I can even look at the vmsas
source to figure it out -- on our machine, at least,
/usr/src/cmd/vmsas is missing files, and the files there are
older than the ones in /usr/src/cmd/as, which also have VMS
#ifdef's.

Shareable images are highly desirable, but they are not the
default under vms, as they are under unix.  Unless you explicitly
say link/shareable, the executable code will not be shared, and
each user will receive his own, private, in-core copy.  This will
kill performance in the case of a large program that many people
are executing (like a command interpreter or editor) since there
won't be enough physical core and most people will have their
redundant copy of the code swapped out most of the time.

If anyone has looked into this problem, or can just suggest which
vmsas sources are likely to be reliable, I would appreciate any
tips.

Perhaps it would help to use cc -S, and let the vms assembler
take a stab at the assembly language code the unix c compiler
spits out.

Eventually we're going to get DEC's c compiler, which will
probably be able to deal with things properly.

                                         Steve Summit
                                         Tektronix, Inc.
                                         tektronix!tekmdp!stevesu
                                         503-629-1069