I'm glad to see the emacs-lisp work is progressing. As it happens, a
month or so ago I blew some of the dust off my old guile-emacs project
and started working on it again too. This flavor of emacs+guile work
aimed to replace Lisp objects in Emacs with Guile objects at the
lowest level (numbers, cons cells; symbols and such become smobs) and
then work upwards from there.
I've updated to recent Emacs sources and Guile 1.8.6. I've gotten it
to a point where it seems to start up fine in tty mode, reads in (and
does color highlighting of) C files and directories, does some other
basic stuff. I'm tweaking it now to see if I can get more stuff
working (like Cocoa support and "make bootstrap") and do more
extensive testing.
One really big hiccup I've run into, which I've sort of sidestepped
for the moment: Guile is not unexec-friendly.
There is a way to build Emacs so it doesn't use unexec, but it then
has to load a lot of Lisp code at run time, really killing the startup
performance, and I don't think it's tested all that much (e.g., "make
bootstrap" doesn't work even without the Guile hacks). To really make
this project work, I need to be able to link against Guile (static is
fine, and probably necessary), do a bunch of Lisp/Scheme processing,
write out a memory image into a new executable, and later be able to
run that executable.
Any record of current threads needs to go away, and be replaced with
info on the new one-and-only thread in the new process; I'm building
without thread support for now to get around it. Any record of stack
regions to be scanned for SCM objects likewise needs resetting.
Allocated objects must *not* go away, and must continue to be
processed by the garbage collector, so I can't just reinitialize
everything. Assigned smob types must remain in effect, and for now
I'm ignoring the possibility that some smobs may need some kind of
reinitialization. Mutexes... well, I don't know if they need
reinitializing; POSIX is kind of unclear on interactions with
unexec. :-) I expect reinitializing them is probably safe, even if
not required in some implementations.
So... I could use some advice here. Is anyone familiar enough with
these bits of the guts of Guile to be able to point out easily what I
should do to reset the relevant parts of Guile's internal state
without trashing other stuff by mistake? Is this something that could
be useful to anyone outside of Emacs?
Ken
P.S. If anyone wants to take a look at my current work, http://www.mit.edu/~raeburn/guilemacs/guile-emacs.tar.bz2
has a snapshot from tonight.
- guile and emacs: unexec Ken Raeburn
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