"Dean W. Anneser" wrote:
> Though somewhat off-topic, I am trying to port our simulation/control/data_acq
>system to RTLinux.
> Key to the success of this endeavor, is the capability of having one process able to
>read/write
> into the process space of another. In the example provided I can both mmap() and
>read()/write()
> /proc on our current platform. On Linux 2.4.1 (RH7.1) however, neither worked.
>
> A couple of years ago, when I first tried this with RH5.2 (I don't remember the
>Linux version)
> I remember seeing a similar (if not identical) disclaimer to what's in the current
>proc(5)
> manpage. The last sentence gave me hope the capability I was seeking was to be
>implemented
> imminently.
>
> mem This is not the same as the mem (1:1) device, despite the fact that it has
>the
> same device numbers. The /dev/mem device is the physical memory before any
> address translation is done, but the mem file here is the memory of the
>process
> that accesses it. This cannot be mmap(2)'ed currently, and will not be
>until a
> general mmap(2) is added to the kernel. (This might have happened by the
>time
> you read this.)
>
> Either Linux can in some form support this and I'm doing something wrong (and the
>documentation
> is out-of-date); or it is currently not yet possible through /proc.
>
> Thank you for taking the time to read this note. Any help or pointers would be very
>much
> appreciated (I hope someone else has crossed this bridge before me).
Ok.
I think I can see the problem.
The interface to mmab has changed since RTLinux 2.0 (I think this was used with RedHat
5.2). It have been made a
lot easy to use. I RTLinux 3.0 you shold use rtl_mmap module insted. I have posted a
small exampel with this mail.
The docomentation for the mmap module is put in drivers/mmap in the rtlinux kernel
sourch.
/*
* init module
*---------------
* har til opgave at oprette f?aelles datalager
* blot en test af mbuff.
*
* Anders Gnistrup
* email [EMAIL PROTECTED]
* 4/7-01
*-----------------*/
#include <rtl.h>
#include <mbuff.h>
#include <rtl_printf.h>
#include "rt2linux.h"
void *memory;
int init_module(void) {
rt2lMem *mem_ptr;
memory = mbuff_alloc(MEM_NAME, sizeof(rt2lMem));
if(memory!=NULL) {
rtl_printf("did alloc mem\n");
mem_ptr = memory;
mem_ptr->devnr[0].ref = 10;
}
else
rtl_printf("did not alloc at addres %p\n",memory);
return 0;
}
void cleanup_module(void) {
rt2lMem *mem_ptr;
if(memory!=NULL) {
mem_ptr = memory;
rtl_printf("got name and ref %d\n",
mem_ptr->devnr[0].ref);
mbuff_free(MEM_NAME,memory);
}
}
/*
* load from commen arear
* just a test
* -------------------------*/
#include <unistd.h>
#include <stdio.h>
#include <rtlinux/mbuff.h>
#include "rt2linux.h"
void *memory;
int main(void) {
rt2lMem *mem_ptr;
memory = mbuff_alloc(MEM_NAME,sizeof(rt2lMem));
if(memory!=NULL) {
printf("succes in alloc mem\n");
mem_ptr = memory;
printf("ref %d\n",mem_ptr->devnr[0].ref);
mem_ptr->devnr[0].ref = 20;
printf("ref %d\n",mem_ptr->devnr[0].ref);
mem_ptr->devnr[0].newData = 1;
mem_ptr->run = 1;
sleep(1);
printf("ref %d\n",mem_ptr->devnr[0].newData);
mbuff_free(MEM_NAME,memory);
}
else {
printf("error alloc\n");
}
return 0;
}
/*
* faelles datastruktur mellem rt-linux og linux.
* data i header filen definere opbygning af data
* det faelles lager modul, samt navnet pa modulet
*-----------------------------------------------*/
#define MEM_NAME "rt2lMem"
#define MOTOR_RIGHT "motor_right"
#define MOTOR_LEFT "motor_left"
#define DIST_CENCOR "dist cencor"
#define LINE_CENCOR "linecencor"
typedef struct device_ {
int newData; /* new data is ready */
int ref; /* ref to de unit */
int error; /* message to userspace if error */
char name[20]; /* name of the device */
} device;
#define NUMOFDEVICE 4
typedef struct rt2lMem_ {
device devnr[4]; /* 4 devices */
int run; /* regulate devices */
} rt2lMem;
