Testing the Template Driver
This dummy driver merely writes a message to a system log each time
an entry point routine is entered. To test this driver, watch for these
messages to confirm that each entry point routine is successfully entered.
The cmn_err(9F) function writes low priority messages such as the messages defined in
this dummy driver to /dev/log. The syslogd(1M) daemon reads messages from /dev/log and
writes low priority messages to /var/adm/messages.
In a separate window, enter the following command and monitor the output as
you perform the tests described in the remainder of this section:
% tail -f /var/adm/messages
Adding the Template Driver
Make sure you are user root when you add the driver. Use the
add_drv(1M) command to add the driver:
# add_drv dummy
You should see the following messages in the window where you are
viewing /var/adm/messages:
date time machine dummy: [ID 513080 kern.notice] NOTICE: Inside _info
date time machine dummy: [ID 874762 kern.notice] NOTICE: Inside _init
date time machine dummy: [ID 678704 kern.notice] NOTICE: Inside dummy_attach
The _info(9E), _init(9E), and attach(9E) entry points are called in that order when
you add a driver.
The dummy driver has been added to the /devices directory:
% ls -l /devices/pseudo | grep dummy
drwxr-xr-x 2 root sys 512 date time dummy@0
crw------- 1 root sys 92, 0 date time dummy@0:0
The dummy driver also is the most recent module listed by modinfo(1M):
% modinfo
Id Loadaddr Size Info Rev Module Name
180 ed192b70 544 92 1 dummy (dummy driver)
The module name, dummy driver, is the value you entered for the second member
of the modldrv(9S) structure. The value 92 is the major number of this
module.
% grep dummy /etc/name_to_major
dummy 92
The Loadaddr address of ed192b70 is the address of the first instruction in
the dummy driver. This address might be useful, for example, in debugging.
% mdb -k
> dummy`_init $m
BASE LIMIT SIZE NAME
ed192b70 ed192ff0 480 dummy
> $qThe dummy driver also is the most recent module listed by prtconf(1M) in the
pseudo device section:
% prtconf -P
pseudo, instance #0
dummy, instance #0 (driver not attached)A driver is automatically loaded when a device that the driver manages is
accessed. A driver might be automatically unloaded when the driver is not in
use.
If your driver is in the /devices directory but modinfo(1M) does not list
your driver, you can use either of the following methods to load your
driver:
Reading and Writing the Device
Make sure you are user root when you perform the tests described in
this section. If you are not user root, you will receive “Permission denied”
error messages when you try to access the /devices/pseudo/dummy@0:0 special file. Notice the permissions
that are shown for /devices/pseudo/dummy@0:0 in Adding the Template Driver.
Test reading from the device. Your dummy device probably is named /devices/pseudo/dummy@0:0. The
following command reads from your dummy device even if it has a slightly different
name:
# cat /devices/pseudo/dummy*
You should see the following messages in the window where you are
viewing /var/adm/messages:
date time machine dummy: [ID 136952 kern.notice] NOTICE: Inside dummy_open
date time machine dummy: [ID 623947 kern.notice] NOTICE: Inside dummy_getinfo
date time machine dummy: [ID 891851 kern.notice] NOTICE: Inside dummy_prop_op
date time machine dummy: [ID 623947 kern.notice] NOTICE: Inside dummy_getinfo
date time machine dummy: [ID 891851 kern.notice] NOTICE: Inside dummy_prop_op
date time machine dummy: [ID 623947 kern.notice] NOTICE: Inside dummy_getinfo
date time machine dummy: [ID 709590 kern.notice] NOTICE: Inside dummy_read
date time machine dummy: [ID 550206 kern.notice] NOTICE: Inside dummy_close
Test writing to the device:
# echo hello > `ls /devices/pseudo/dummy*`
You should see the following messages in the window where you are
viewing /var/adm/messages:
date time machine dummy: [ID 136952 kern.notice] NOTICE: Inside dummy_open
date time machine dummy: [ID 623947 kern.notice] NOTICE: Inside dummy_getinfo
date time machine dummy: [ID 891851 kern.notice] NOTICE: Inside dummy_prop_op
date time machine dummy: [ID 623947 kern.notice] NOTICE: Inside dummy_getinfo
date time machine dummy: [ID 891851 kern.notice] NOTICE: Inside dummy_prop_op
date time machine dummy: [ID 623947 kern.notice] NOTICE: Inside dummy_getinfo
date time machine dummy: [ID 672780 kern.notice] NOTICE: Inside dummy_write
date time machine dummy: [ID 550206 kern.notice] NOTICE: Inside dummy_close
As you can see, this output from the write test is almost
identical to the output you saw from the read test. The only difference
is in the seventh line of the output. Using the cat(1) command causes the
kernel to access the read(9E) entry point of the driver. Using the
echo(1) command causes the kernel to access the write(9E) entry point of the driver.
The text argument that you give to echo(1) is ignored because this
driver does not do anything with that data.
Removing the Template Driver
Make sure you are user root when you unload the driver. Use the
rem_drv(1M) command to unload the driver and remove the device from the /devices
directory:
# rem_drv dummy
You should see the following messages in the window where you are
viewing /var/adm/messages:
date time machine dummy: [ID 513080 kern.notice] NOTICE: Inside _info
date time machine dummy: [ID 617648 kern.notice] NOTICE: Inside dummy_detach
date time machine dummy: [ID 812373 kern.notice] NOTICE: Inside _fini
The dummy device is no longer in the /devices directory:
# ls /devices/pseudo/dummy*
/devices/pseudo/dummy*: No such file or directory
The next time you want to read from or write to the
dummy device, you must load the driver again using add_drv(1M).
You can use the modunload(1M) command to unload the driver but not remove
the device from /devices. Then the next time you read from or write
to the dummy device, the driver is automatically loaded.
Press Control-C to stop tailing the /var/adm/messages messages.
