how does one debug a SEGV in scm_threads_prehistory?

[Bruce Korb]

Our main development server was "upgraded" to 64 bits, but mostly
still runs 32 bit software,
so this is from a 32 bit build on a 64 bit platform.  Naturally, this
all works on 32 on 32 and
on 64 on 64.  But with 32 on 64, not so well:

Program received signal SIGSEGV, Segmentation fault.
0xb7f482fe in scm_threads_prehistory () from /usr/lib/libguile.so.17
(gdb) bt
#0  0xb7f482fe in scm_threads_prehistory () from /usr/lib/libguile.so.17
#1  0xb7f4834b in scm_i_thread_sleep_for_gc () from /usr/lib/libguile.so.17
#2  0xb7f48375 in scm_i_thread_put_to_sleep () from /usr/lib/libguile.so.17
#3  0xb7f2f3e4 in scm_i_string_writable_chars () from /usr/lib/libguile.so.17
#4  0xb7f2f53d in scm_c_string_set_x () from /usr/lib/libguile.so.17
#5  0xb7f23839 in scm_read_token () from /usr/lib/libguile.so.17
#6  0xb7f23fcc in scm_lreadr () from /usr/lib/libguile.so.17
#7  0xb7f23c87 in scm_lreadrecparen () from /usr/lib/libguile.so.17
#8  0xb7f245d8 in scm_lreadr () from /usr/lib/libguile.so.17
#9  0xb7f23cfd in scm_lreadrecparen () from /usr/lib/libguile.so.17
#10 0xb7f245d8 in scm_lreadr () from /usr/lib/libguile.so.17
#11 0xb7f24c43 in scm_read () from /usr/lib/libguile.so.17
#12 0x08056634 in ag_scm_c_eval_string_from_file_line (
    pzExpr=0x8075ce0 "(if (> (string-length shell-cleanup) 0) (shell
shell-cleanup) )", pzFile=0x8075cc8 "../../agen5/autogen.c", line=237)
    at ../../agen5/expGuile.c:113
#13 0x0804e03c in doneCheck () at ../../agen5/autogen.c:236
#14 0xb7d053b0 in exit () from /lib/tls/i686/cmov/libc.so.6
#15 0x0804dd56 in inner_main (argc=4, argv=0xbfb38274)
    at ../../agen5/autogen.c:90
#16 0xb7ef9f72 in gh_enter () from /usr/lib/libguile.so.17
#17 0xb7f06224 in scm_boot_guile () from /usr/lib/libguile.so.17
#18 0xb7ed8bc2 in scm_char_upcase () from /usr/lib/libguile.so.17
#19 0xb7f4a025 in scm_c_catch () from /usr/lib/libguile.so.17
#20 0xb7ed9107 in scm_i_with_continuation_barrier ()
   from /usr/lib/libguile.so.17
#21 0xb7ed91e1 in scm_c_with_continuation_barrier ()
   from /usr/lib/libguile.so.17
#22 0xb7f49309 in scm_i_with_guile_and_parent () from /usr/lib/libguile.so.17
#23 0xb7f4935e in scm_with_guile () from /usr/lib/libguile.so.17
#24 0xb7f061bf in scm_boot_guile () from /usr/lib/libguile.so.17
#25 0xb7ef9f45 in gh_enter () from /usr/lib/libguile.so.17
#26 0x0804de00 in main (argc=4, argv=0xbfb38274) at ../../agen5/autogen.c:115