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Commit efd9aa3b authored by pw's avatar pw
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I just finished making load-foreign work on SGIs, along with fixing calling of

foreign functions taking floating-point arguments after integer arguments but
before the fourth argument (more or less; mips has unusual C calling
conventions), and making cmucl work on IRIX 6.2 on the Onyx (where the system
page size has changed). I've included the patches below, along with some
discussion of the changes and a couple of problems with cmucl's interaction with
dynamic loading. Also, there's a misc change to make ioctls work (I'm not sure
for what version the released code worked, but it doesn't work on anything I
have). The patches do not fix the R10000; cmucl continues to not work on it (O2
and Octane).

The fixes make cmucl on the sgi use shared libraries so it can use dlopen et al
in load-foreign; this is based on the solaris implementation. The problem with
this is that the addresses of foreign variables are included directly in the
dumped lisp image (without relocation on loading), which might result in a
problem if cmucl is run with newer shared libraries than those it was compiled
and dumped with. As far as I can tell, for the SGI at least, this does not
affect function calls because the addresses used (and included in the dumped
image) are those of stub routines that jump to the actual routines, thus are
located in the executable proper rather than in the shared libraries, and so
shouldn't be changed by a new version of the shared library.

Unfortunately, this is not the case for global variables. Fortunately, there
appear to only be two foreign variables used by cmucl in any of its system code
winding up in the dumped image: errno and tzname. Apparently, Solaris relocates
data references in dsos to match the program, while IRIX relocates data
references in the program to match the dso. Thus, on Solaris, you don't need to
do anything special for cmucl to work with a newer runtime libc, but on IRIX it
gets the wrong value of errno and tzname. Unfortunately, the address of errno is
different between irix 6.2, 6.3, and 6.4 (all of which we have to have because
SGI doesn't have a single cross-platform OS version yet), which would require a
different lisp.core for each machine (you just need to run mk-lisp, not
recompile) if it weren't for the hack below. But fortunately again, a lisp
compiled for one version seems to be able to run on another version well enough
to generate the new lisp.core (presumably the worst that would happen is that
error messages could be confusing). It would be really nice to avoid this
problem. Perhaps some kind of relocation table could be added to the dumped
image format? I don't know enough about the system to know how possible or
ridiculous that suggestion is, unfortunately. Is the Solaris behavior guaranteed
to be the same in future releases? If not, or if any other platforms have the
irix behavior, this might become a more general problem. In the meantime, we use
a hack: we *define* errno in undefineds.c rather than just referencing it; this
results in warnings from the linker, but it resolves the conflict in favor of
the definition in the program, relocating libc to match, thus fixing this
problem for errno. The other global variables, tzname et al, can't be fixed this
way as easily because they're listed as weak symbols, essentially aliases for
the real symbol, so redefining them wouldn't cause libc to reference the new
version. Thus, as long as you don't use tzname, there's no problem right now
(although there may be if any other library global variables are used in cmucl
in the future). The definition of tzname is in a progn preceeded by a comment
which says not to use it, so hopefully it's not in fact used and therefore not a
problem.


These patches have been tested on an R5000 O2 running irix 6.3 and a dual R4400
Onyx running irix 6.2. A previous version of these patches (for 17f) was tested
on the onyx when it was running 5.3 (I think, maybe 5.2). The patches here are
from the main branch of the CVS tar as of August 13. Incidentally, it was quite
painful figuring out how to compile and bootstrap the current sources under the
distributed irix 18a binary, even without trying :new-random or :signed-array
(which I haven't tried to do yet); it might be nice to put a newer binary up...
parent 2e74eedf
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