device_read example

[Shakthi Kannan]

Greetings!

I am trying a simple device_read operation from GNU
Hurd to gnumach-1-branch.

In gnumach-1-branch/i386/i386at/lpr.c, I have:

lpropen(dev, flag, ior)
int dev;
int flag;
#ifdef  MACH_KERNEL
io_req_t ior;
#endif  MACH_KERNEL
{
  printf("lpr.c: lpropen()...\n");
  return;
}

lprread(dev, ior)
int     dev;
io_req_t ior;
{
  register int err;
  unsigned long data = 0x5a5a;
  printf("lpr.c: lprread()...\n");
  ...

I have a simple test function on GNU Hurd that

1. gets_privileged_ports from device_t
  
  error_t err;
  device_t device_master;
  err = get_privileged_ports (0, &device_master);

2. calls device_open

  err = device_open (device_master, D_READ | D_WRITE,
"lpr", &lpr_dev);

But, when I try to do device_read, it doesn't print
message in the device_read function in
gnumach-1-branch/i386/i386at/lpr.c

3. calling device_read

  unsigned long result;
  mach_msg_type_number_t data_cnt = sizeof (result); 
  err = device_read (device_master, 0, -1, sizeof
(result), (void *) &result, &data_cnt);

  if (err)
    {
      printf ("device_read_inband error\n");
      return err;
    }

When I run the above program, it does call the
device_open in gnumach driver, but, for device_read it
exits with the device_read_inband error message.

Am I missing something here? Any help is appreciated.

Thanks,

SK

------------------------------------------------------------
Shakthi Kannan, MS
Software Engineer, Specsoft (Hexaware Technologies)
[E]: shaks@shakthimaan.com           [M]: (91) 98407-87007
[W]: http://www.shakthimaan.com      [L]: Chennai, India
------------------------------------------------------------


                
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