Below is a pared down version of my rt_process.c. I've cut out all COMEDI
data acquisition and FIFO stuff. I'm running rtlinux-2.3 on a single
processor computer without SMP support. I use mbuff-0.7.0 for shared
memory.
If I compile it with:
gcc -D INT_G -I/usr/src/rtl/linux/include -I/usr/src/rtlinux-2.3
-I/usr/src/rtlinux-2.3/include -I/usr/src/rtlinux-2.3/include/posix -Wall
-Wstrict-prototypes -O2 -D__RTL__ -D__KERNEL__ -DMODULE -pipe -fno-strength-reduce
-m486 -malign-loops=2 -malign-jumps=2 -malign-functions=2 -DCPU=686 -g -c -o
rt_process_tmp.o rt_process.c; ld -r -static rt_process_tmp.o -o rt_process.o
-L/usr/lib -lm; rm -f rt_process_tmp.o
my shared memory variable g is int, and the process runs fine.
If I compile it with:
gcc -D FLOAT_G -I/usr/src/rtl/linux/include -I/usr/src/rtlinux-2.3
-I/usr/src/rtlinux-2.3/include -I/usr/src/rtlinux-2.3/include/posix -Wall
-Wstrict-prototypes -O2 -D__RTL__ -D__KERNEL__ -DMODULE -pipe -fno-strength-reduce
-m486 -malign-loops=2 -malign-jumps=2 -malign-functions=2 -DCPU=686 -g -c -o
rt_process_tmp.o rt_process.c; ld -r -static rt_process_tmp.o -o rt_process.o
-L/usr/lib -lm; rm -f rt_process_tmp.o
my shared memory variable g is float, and my computer occasionally, but
not always, crashes at the first occurence of: sh_mem->g/=2;
Note that I think (although it's difficult to know for sure with this sort
of "random" phenomenon) that if it runs fine once, it seems that it will
always run fine unless I reboot the computer. After rebooting, it may run
fine again. After rebooting again, it may run fine again, etc. But, sooner
or later, I'll reboot, insmod rt_process, and my system crashes.
The code is at the end of this message, preceded by some possibly useful
module and dmesg stuff.
Any ideas?
Thanks,
Dave
-----------
This is what modules I have running when it works - cat /proc/modules:
rt_process 1068 0 (unused)
mbuff 6084 1 [rt_process]
rtl_fifo 7892 0 (unused)
rtl_posixio 6716 0 [rtl_fifo]
rtl_sched 5776 0 [rt_process]
kcomedilib 3136 0 (unused)
ni_atmio 14408 0
comedi 14028 0 [kcomedilib ni_atmio]
rtl_time 11036 0 [rt_process rtl_posixio rtl_sched
kcomedilib ni_atmio comedi]
------------
This is dmesg after a brief successful run (terminated by rmmod):
dmesg
mbuff: kernel shared memory driver v0.7.0 for Linux 2.2.14-rtl2.3
mbuff: (C) Tomasz Motylewski et al., GPL
mbuff: registered as MISC device minor 254
allocated 1048576 bytes at cc849000 for cb2a3a20(default)
djc_float_crasher: requesting allocation of 8 bytes for sh_mem from mbuff:
allocated 4096 bytes at cc94c000 for cb2a3c60(djc_float_crasher)
djc_float_crasher: acquisition started at 1000 Hz (status 0)
djc_float_crasher g=50000000
djc_float_crasher g=25000000
djc_float_crasher g=12500000
djc_float_crasher g=6250000
deallocating kernel buffer at cc94c000(djc_float_crasher), count=0.
djc_float_crasher: deleted RT task (status 0) after 5461 cycles (~5
seconds).
unloading mbuff
deallocating kernel buffer at cc849000(default), count=0.
mbuff device deregistered
---------
/************ rt_process.c **************/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/version.h>
#include <linux/errno.h>
#include <rtl.h>
#include <rtl_fifo.h>
#include <rtl_sched.h>
#include <rtl_sync.h>
#include <rtl_debug.h>
#include <float.h> //necessary for floating point ops?
#include <asm/types.h> //necessary for floating point ops?
#include "/usr/src/rtl/drivers/mbuff/mbuff.h" //mbuff: shared memory dyn. alloc
#define RT_HZ 1000 //rt_process loop frequency
#define RT_PROCESS_ID "djc_float_crasher" //text ID for this process
int init_module(void); //set up RT stuff
void cleanup_module(void); //clean up RT stuff
void init_shared_mem(void); //set up RT shared memory
pthread_t daq_task; //main RT task
typedef struct {
int scan_index; //index holding current analog input scan number
#ifdef FLOAT_G
float g; //g feedback proportionality control parameter
#endif
#ifdef INT_G
int g; //g feedback proportionality control parameter
#endif
} SharedMemStruct;
volatile SharedMemStruct *sh_mem; //define mbuff shared memory
void *daq(void *arg) { /* this task reads and writes data to a DAQ board */
while (1) /* must loop, b/c it is a periodic task */
{
sh_mem->scan_index++; //increment scan_index counter
/* normally my COMEDI analog input and output goes here;
instead here's a dumb computation*/
if ((sh_mem->scan_index>2000)&&(!(sh_mem->scan_index%200))){
sh_mem->g/=2;
rtl_printf(RT_PROCESS_ID " g=%d\n",(int)sh_mem->g);
}
pthread_wait_np(); //wait until beginning of next period
}
}
int init_module(void) {
int ret; //return value from function calls
pthread_attr_t attr;
struct sched_param sched_param;
init_shared_mem(); //initialize shared memory
/* create the realtime task */
pthread_attr_init(&attr);
sched_param.sched_priority = 1;
pthread_attr_setschedparam(&attr, &sched_param);
if ((ret = pthread_create(&daq_task, &attr, daq, (void *)1))) {
goto init_error;
}
/* make task periodic: run at a rate of RT_HZ */
ret = pthread_make_periodic_np(daq_task, gethrtime(),NSECS_PER_SEC/RT_HZ);
if (ret) goto init_error;
rtl_printf(RT_PROCESS_ID ": acquisition started at %d Hz (status %d)\n",
RT_HZ, ret);
return 0;
//allow floating point operations ... see RTLinux FAQ
pthread_setfp_np (daq_task, 1);
init_error:
rtl_printf(RT_PROCESS_ID ": can't initalize RT task (error %d)\n", ret);
return 1;
}
void init_shared_mem(void) { // Initialize the rtlinux shared memory
//allocate mbuff Shared Memory structure
rtl_printf(RT_PROCESS_ID ": requesting allocation of %d bytes for sh_mem from
mbuff:\n",
sizeof(SharedMemStruct));
sh_mem=(volatile SharedMemStruct*)mbuff_alloc(RT_PROCESS_ID,
sizeof(SharedMemStruct));
//initialize shared memory variables ... see rt_process.h for definitions
sh_mem->scan_index=0;
sh_mem->g=100000000; //TRUE;
}
void cleanup_module(void) {
int ret;
//delete daq_task
ret= pthread_delete_np(daq_task);
rtl_printf(RT_PROCESS_ID ": deleted RT task (status %d) after %d cycles (~%d
seconds).\n",
ret, sh_mem->scan_index, sh_mem->scan_index/RT_HZ);
//free up mbuff shared memory
mbuff_free(RT_PROCESS_ID,sh_mem);
}
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