Re: Sparc64 and ATI fb, cannot mmap() - why?

From: Francis Galiegue (fg@mandrakesoft.com)
Date: Tue Jun 20 2000 - 05:35:29 EST

On Tue, 20 Jun 2000, David S. Miller wrote:

> Date: Tue, 20 Jun 2000 12:09:16 +0200 (CEST)
> From: Francis Galiegue <fg@mandrakesoft.com>
>
> All is in the subject...
>
> What kernel, and what is trying to mmap it (the X server I presume)?
>

Kernel is 2.2.16, and trying to mmap() from a custom application. The following
code works for ALL machines except the Ultra5 with the ATI framebuffer, and I
don't know why...

#include <stdio.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/ioctl.h>
#include <linux/fb.h>

#define croak(x) do {\
        perror(x);\
        exit(1);\
} while (0)
        
int main(void) {
        int fd;
        char *foo;
        struct fb_fix_screeninfo x;
        struct fb_var_screeninfo v;
        size_t screensize;

        fd = open("/dev/fb0", O_RDWR);

        if (fd == -1)
                croak("open failed");

        if (ioctl(fd, FBIOGET_VSCREENINFO, &v))
                croak("ioctl FBIOGET_VSCREENINFO failed");
        
        if (ioctl(fd, FBIOGET_FSCREENINFO, &x))
                croak("ioctl FBIOGET_FSCREENINFO failed");

        screensize = v.xres * v.yres * v.bits_per_pixel / 8;

        foo = mmap(x.mmio_start, screensize, PROT_WRITE, MAP_SHARED, fd, 0);

        if (foo == MAP_FAILED)
                croak("mmap failed");

        fprintf(stderr,"Success\n");

        memset(foo, 0xaa, screensize);

        sleep(5);
        munmap(foo, screensize);
        close(fd);
        return 0;
} 

-- 
fg

"You can tune a filesystem but you can't tuna fish" (HP/UX' tunefs manpage)

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