Specs:
rtl3.1 with linux 2.4.18 (sourced from
http://bernia.disca.upv.es/rtportal) on an i386 RedHat7.3 system;
gdb-5.1.90CVS-5
I have compiled a modified version of the
$(RTLINUX_DIR)/examples/hello.c program to familiarise myself with the
debugging process (the source is included hereunder as also the commands
used to compile the source)
(All lines with a '>' preceding are source and terminal outputs)
>
>/*****************************************************************************************************************
>
>*****************************************************************************************************************
>
> #include <rtl.h>
> #include <time.h>
> #include <pthread.h>
> #include <rtl_debug.h>
>
> pthread_t thread = NULL;
>
> void * start_routine(void *arg) {
>
>
> // Most of the variables are only declared and initialized and unused otherwise
>
> float gen_count = 0.0;
> int gen_var = 0;
> char gen_str[20] = "test string";
> char option = 't';
>
> breakpoint();
>
> while (1) {
> pthread_wait_np ();
> rtl_printf("Debug count = %x\n", gen_count++);
> if (gen_count > 10.0) {
> gen_var = 1;
> }
> }
> return 0;
> }
>
> int init_module(void) {
>
> int i;
> struct sched_param p = { 0 };
> pthread_attr_t attr;
>
>
> pthread_attr_init(&attr);
> p . sched_priority = 1;
> pthread_attr_setschedparam (&attr,&p);
>
> i = pthread_create (&thread, &attr, start_routine, (void *)1);
>
> pthread_make_periodic_np (thread, gethrtime(), 500000000);
>
> return (i);
>
> }
>
> void cleanup_module(void) {
> pthread_delete_np (thread);
> }
>
>
>****************************************************************************************************************
>
>****************************************************************************************************************/
> [root@Prithvi hello]# make clean; make
> rm -f *.o
> kgcc -D__KERNEL__ -Wall -Wstrict-prototypes -Wno-trigraphs -fno-strict-aliasing
>-fno-common -pipe -march=i586 -DMODULE -g -D__RTL__ -D_LOOSE_KERNEL_NAMES -O2
>-I/usr/src/rtlinux-3.1/linux/include -I/usr/src/rtlinux-3.1/include
>-I/usr/src/rtlinux-3.1/include/compat -I/usr/src/rtlinux-3.1/include/posix -c -o
>hello.o hello.c
> hello.c: In function `start_routine':
> hello.c:13: warning: unused variable `option'
> hello.c:12: warning: unused variable `gen_str'
> [root@Prithvi hello]# rtlinux start
> Warning: loading /usr/rtlinux-3.1/modules/mbuff.o will taint the kernel: no license
> Warning: loading /usr/rtlinux-3.1/modules/rtl.o will taint the kernel: no license
> Warning: loading /usr/rtlinux-3.1/modules/rtl_time.o will taint the kernel: no
>license
> Warning: loading /usr/rtlinux-3.1/modules/rtl_posixio.o will taint the kernel: no
>license
> Warning: loading /usr/rtlinux-3.1/modules/rtl_fifo.o will taint the kernel: no
>license
> Warning: loading /usr/rtlinux-3.1/modules/rtl_sched.o will taint the kernel: no
>license
> Warning: loading /usr/rtlinux-3.1/modules/rtl_debug.o will taint the kernel: no
>license
>
> Scheme: (-) not loaded, (+) loaded
> (+) mbuff
> (+) rtl_debug
> (+) rtl_fifo
> (+) rtl
> (+) rtl_posixio
> (+) rtl_sched
> (+) rtl_time
>
>
> [root@Prithvi hello]# insmod hello.o
> Warning: loading hello.o will taint the kernel: no license
>
> [root@Prithvi hello]# dmesg -c
> mbuff: kernel shared memory driver v0.7.2 for Linux 2.4.18-rtl31
> mbuff: (C) Tomasz Motylewski et al., GPL
> mbuff: registered as MISC device minor 254
> RTLinux Extensions Loaded (http://www.fsmlabs.com/)
> RTLinux Debugger Loaded (http://www.fsmlabs.com/)
> rtl_debug: exception 0x3 in hello (EIP=0xc88570a0), thread id 0xc2358000; (re)start
>GDB to debug
>
> [root@Prithvi hello]# gdb hello.o
>
> GNU gdb Red Hat Linux (5.1.90CVS-5)
> Copyright 2002 Free Software Foundation, Inc.
> GDB is free software, covered by the GNU General Public License, and you are
> welcome to change it and/or distribute copies of it under certain conditions.
> Type "show copying" to see the conditions.
> There is absolutely no warranty for GDB. Type "show warranty" for details.
> This GDB was configured as "i386-redhat-linux"...
>
> (gdb) dbg
> [New Thread -1036681216]
> warning: (Internal error: pc 0xc88570a0 in read in psymtab, but not in symtab.)
>
> [Switching to Thread -1036681216]
> warning: (Internal error: pc 0xc88570a0 in read in psymtab, but not in symtab.)
>
> warning: (Internal error: pc 0xc88570a0 in read in psymtab, but not in symtab.)
>
> warning: (Internal error: pc 0xc88570a0 in read in psymtab, but not in symtab.)
>
> 0xc88570a0 in start_routine () at hello.c:15
> 15 breakpoint();
> warning: shared library handler failed to enable breakpoint
> warning: (Internal error: pc 0xc88570a0 in read in psymtab, but not in symtab.)
>
> warning: (Internal error: pc 0xc88570a0 in read in psymtab, but not in symtab.)
>
> (gdb) info locals
> warning: (Internal error: pc 0xc88570a0 in read in psymtab, but not in symtab.)
>
> No symbol table info available.
> warning: (Internal error: pc 0xc88570a0 in read in psymtab, but not in symtab.)
>
> (gdb) quit
> The program is running. Exit anyway? (y or n) y
I downgraded to gdb-4.18-11 and this is the output
> [root@Prithvi hello]# rtlinux start
>
> Warning: loading /usr/rtlinux-3.1/modules/mbuff.o will taint the kernel: no license
> Warning: loading /usr/rtlinux-3.1/modules/rtl.o will taint the kernel: no license
> Warning: loading /usr/rtlinux-3.1/modules/rtl_time.o will taint the kernel: no
>license
> Warning: loading /usr/rtlinux-3.1/modules/rtl_posixio.o will taint the kernel: no
>license
> Warning: loading /usr/rtlinux-3.1/modules/rtl_fifo.o will taint the kernel: no
>license
> Warning: loading /usr/rtlinux-3.1/modules/rtl_sched.o will taint the kernel: no
>license
> Warning: loading /usr/rtlinux-3.1/modules/rtl_debug.o will taint the kernel: no
>license
>
> Scheme: (-) not loaded, (+) loaded
> (+) mbuff
> (+) rtl_debug
> (+) rtl_fifo
> (+) rtl
> (+) rtl_posixio
> (+) rtl_sched
> (+) rtl_time
>
>
> [root@Prithvi hello]# insmod hello.o
>
> Warning: loading hello.o will taint the kernel: no license
>
> [root@Prithvi hello]# dmesg -c
>
> mbuff: kernel shared memory driver v0.7.2 for Linux 2.4.18-rtl31
> mbuff: (C) Tomasz Motylewski et al., GPL
> mbuff: registered as MISC device minor 254
> RTLinux Extensions Loaded (http://www.fsmlabs.com/)
> RTLinux Debugger Loaded (http://www.fsmlabs.com/)
> rtl_debug: exception 0x3 in hello (EIP=0xc88570a0), thread id 0xc50f0000; (re)start
>GDB to debug
>
> [root@Prithvi hello]# gdb hello.o
>
> GNU gdb 19991004
> Copyright 1998 Free Software Foundation, Inc.
> GDB is free software, covered by the GNU General Public License, and you are
> welcome to change it and/or distribute copies of it under certain conditions.
> Type "show copying" to see the conditions.
> There is absolutely no warranty for GDB. Type "show warranty" for details.
> This GDB was configured as "i386-redhat-linux"...
>
> (gdb) dbg
> [New Pid -988872704]
> [Switching to Pid -988872704]
> 0xc88570a0 in start_routine (arg=0x1) at hello.c:15
> 15 breakpoint();
>
> (gdb) info locals
> gen_count = 0
> gen_str = "test string"
>
The warnings about the internal error and the failure of the shared
library handler to enable the breakpoint have disappeared, but the local
variables in the function *start_routine have not been recognized and
read in. They are however read in if all of them are declared static. In
the latter case, a
> (gdb) print option
statement provides the output
> $1 = 116 't'
1. What do the warning messages in gdb-5.1.90CVS-5 mean ?
2. Why are all the symbols not read in completely in gdb-4.18-11 ?
3. Why are all the symbols visible *when declared static* ?
4. What does the 116 in the output of "print option" stand for ?
An earlier mail in the archives does mention that the later versions of
gdb (>5.0) have a bug but that the debugger seems to work fine with
gdb-4.18 . I am unable to figure out at what point the problem could be.
The situation is exactly the same on the same machine with rtl2.3, linux
2.2.14 and RedHat6.2, with gdb-4.18-11
Any help would be greatly appreciated.
Thanx
VC
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