[Openmcl-devel] Troubleshooting FFI calls on ARM

Jeremy Shoemaker jeremy at codingkoi.com
Wed Jun 19 13:45:36 PDT 2019


I've been playing around with CCL on a reMarkable tablet, which is an e-ink
tablet running Linux on ARM, and I got it working for the most part
(quicklisp, swank, remote editing from Emacs), but I want to start playing
around with accessing the e-ink display and the Wacom digitizer that it
has, which requires some low level syscalls.

That's all way ahead of where I am right now though. I'm trying to get FFI
working, calling basic functions in the C library to confirm that it works,
but I'm running into segmentation faults, and I'm not quite sure how to
diagnose the problem.

Specifically what I'm doing is, I've copied the ARM version over to the
device, and unpacked the tarball. Then, I do:

~ $ cd ccl
~/ccl $ ./armcl --no-init
Clozure Common Lisp Version 1.11.5/v1.11.5  (LinuxARM32)

For more information about CCL, please see http://ccl.clozure.com.

CCL is free software.  It is distributed under the terms of the Apache
Licence, Version 2.0.
? (#_getpid)
Segmentation fault (core dumped)
~/ccl $

Is there something obvious here I'm missing that would explain why it's
trying to read invalid memory? Is there some rebuild steps I need to do to
get the FFI directory configured properly?

I've tried using (external "getpid"), and I get back the addresses of the
external-entry-point for getpid and lib.so.6 but I'm not sure how to
confirm if those are pointing to the right locations.

I realize this is probably some esoteric configuration that I'm trying to
play around with, and that here may be dragons, but any help would be
greatly appreciated.

Jeremy Shoemaker
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