freeBSD device driver (use struct uio)

Applications Programming
1

Hi, everybody

I have next problem...

1) My Example program code
void main()
{
int fd;
int len;
int buf[256];
fd=open("mydev", O_RDONLY);
lseek(fd, 0, SEEK_SET);
len=read(fd, buf, sizeof(buf));
}

2) My Example Driver code

static int mydev_read(dev_t dev, ?, ?, struct uio* uio)
{
int newbuf[10];
int lennewbuf;
lenbuf=uio->uio_resid; //this is size of programm buffer (see up sizeof(buf))
uio->uio_resid=10*sizeof(int); //I try set new size returned buffer
moveuio(?,?,?,?);//I copy data to program buffer
return 0;
}

3) And Question...
Why is len variable (in Program code) after call read() == sizeof(buf), but I set in Driver code uio_resid to value
10*sizeof(int)?

It's All :cool: