Memory fault in32()

QNX DEVELOPERS Realtime and Embedded
1

hi,

I’m using in32 and out32 function to read or write in register but I get au memory fault, in debug mode it indicate segmentation fault !

just a simple code :

[code]#include <stdlib.h>
#include <stdio.h>
#include <hw/inout.h>
#include <sys/neutrino.h>
#include <stdint.h>
#include <sys/mman.h>

int main(int argc, char *argv[]) {

int data=0;
ThreadCtl( _NTO_TCTL_IO, 0 );
//out32(0x20ac004, 0 );
mmap_device_io( 4,0x20ac004 );
data=in32(0x20ac004 );

printf("data = %x",data);


return EXIT_SUCCESS;

}
[/code]

2

Are you running as root? To perform the indicated function with ThreadCtl() you need to be root. Other than that your code looks good.

3

Actually isn’t he supposed to use the return pointer from mmap_device_io like so:

uintptr_t ptr;

ptr = mmap_device_io( 4,0x20ac004 );
data=in32( ptr );

Tim

4

Ideally yes. On some architecture this might be required. In general, no.

5

I agree with Tim. This is the correct code for any architecture.

#include <stdlib.h>
#include <stdio.h>
#include <hw/inout.h>
#include <sys/neutrino.h>
#include <stdint.h>
#include <sys/mman.h>

int main(int argc, char *argv[]) {
int data = 0;
uintptr_t hndl;

ThreadCtl( _NTO_TCTL_IO, 0 );
hndl = mmap_device_io( 4, (long long)0x20ac004 );
data = in32( hndl );
printf(“data = %x”,data);
return EXIT_SUCCESS;
]

6

Thanks evreyone,

using a pointer returned from mmap_device_io and print it fixed the problem.