Well this is a weird one. When I tried defcvar to define *step-rk8pd* before, I got a memory fault. When I re-tried it recently, it worked. Perhaps I didn't actually redefine it the first time when I thought I had.
Thanks to everyone for the help.
Liam
On 10/16/07, Cyrus Harmon ch-lisp@bobobeach.com wrote:
That's because you're looking at a lisp stack with gdb which doesn't understand the lisp stack structure. You want to call backtrace_from_fp with the frame pointer which should be in one of the registers, rsp maybe?
You could try asking about debugging lisp from gdb on #lisp.
good luck,
Cyrus
On Oct 16, 2007, at 7:00 PM, Liam Healy wrote:
Yes, I've tried that. The problem is that I get a backtrace like so: (gdb) where #0 0x0000001000159475 in ?? () #1 0x0000000000000010 in ?? () #2 0x0000000000001000 in ?? () #3 0x000000100015afa1 in ?? () #4 0x000000100015b09f in ?? () #5 0x0000000040000017 in ?? () #6 0x000000100015afa1 in ?? () #7 0x00000010004683a3 in ?? () #8 0x00002b8a3182f800 in ?? () #9 0x000000004000004f in ?? () #10 0x0000001002f32767 in ?? () #11 0x0000000040000017 in ?? () #12 0x000000100015afa1 in ?? () #13 0x000000004000004f in ?? () #14 0x0000000000000000 in ?? ()
Not very informative. I've even tried to recompile SBCL with symbols not stripped, but it doesn't help.
Liam
On 10/9/07, Daniel Herring dherring@tentpost.com wrote:
Have you tried attaching gdb to the lisp process? I spot most of my errors by setting breakpoints and looking at the actual function call.
The session would look something like SHELL> ps ax | grep lisp (or sbcl or clisp or...) SHELL> gdb lisp 1234 (where 1234 is the process ID) GDB> print gsl_odeiv_step_rk8pd (this should be the same value you see in lisp) GDB> break gsl_odeiv_step_alloc GDB> continue CL> (call-bad-cffi) (gdb stops lisp when it calls the function) GDB> print gsl_odeiv_step_type (this pointer's value should be the same as before) GDB> detach GDB> quit
- Daniel
On Tue, 9 Oct 2007, Liam Healy wrote:
James,
I tried both
(defvar *step-rk8pd* (cffi:foreign-symbol-pointer "gsl_odeiv_step_rk8pd"))
and
(cffi:defcvar ("gsl_odeiv_step_rk8pd" *step- rk8pd*) :pointer :read-only t)
I'm not clear on what the difference is, but they both give a memory fault.
Liam
On 10/9/07, James Bielman jamesjb@haytonsystems.com wrote:
On Sun, 2007-10-07 at 13:16 -0400, Liam Healy wrote:
I am using CFFI in SBCL on Debian GNU/Linux etch (amd64). I have had a great deal of success interfacing to the GNU scientific library (GSL). Usually, when I get a "memory fault" I quickly can see my mistake in defining the interface, and once fixed, the error goes away.
I can't figure this one out however. The interface is: gsl_odeiv_step * gsl_odeiv_step_alloc (const gsl_odeiv_step_type * T, size_t dim) I attempt to call this with a predefined pointer, (describe *step-rk8pd*) #.(SB-SYS:INT-SAP #X2B31DAEB0328) is a SB-SYS:SYSTEM-AREA- POINTER. and I get a memory fault. What is the best way to debug this?
Hi Liam,
You don't show how you are defining *STEP-RK8PD* here, but I am wondering if what you actually have is the address of that variable.
Are you defining this with DEFCVAR?
James
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