On 05/12/2011 06:15 AM, arethe rtai wrote:
> Hi all:
>     I wirte a share memory program, but I found the share momory does
> not work while I try to take a communication between user space and
> kernel space.
>     The task in kernel is OK, we can get the shared space. But the
> task in user space can not get the share memory.
>     The code of the task in user space as follows:

What happens when the user-space tries to get the shared space?

> 
>  #include <stdio.h>
> #include <unistd.h>
> #include <sys/types.h>
> #include <sys/mman.h>
> #include <sys/stat.h>
> #include <fcntl.h>
> #include <rtai/rtai.h>
> #include <rtai/rtai_shm.h>
> 
> 
> int main(void)
> {
>       unsigned int *adr;
> 
>       adr=(unsigned int *)rt_shm_alloc(0xaaaaa, sizeof(*adr), USE_VMALLOC);
> 
>       if (adr==NULL)
>               printf("NULL pointer find \n");
> 
>       //rt_shm_free(0xaaaaa);
> 
>       printf("%d    line   \n",__LINE__);
> 
>       fflush(stdout);
> 
>       return 0;
>       
> }
> 
> BTW: I added some printf in file src/skins/rtai/shm.c, but they cannot
> be outputted to the console.

I doubt that very much. If printf did not work, a lot of application
would not work on your system.

-- 
                                                                Gilles.

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