How to write driver with load time parameter support?

[cm c]

Thank you very much! It does work!
 
CcM

Dan Nelson <dnelson at allantgroup.com> wrote:
In the last episode (Dec 09), cm c said:
> I'm still not very clear the way to do this. Does this method do set
> the parameters at load time or after load ? Cause Linux can
> insmod abc.o param=123;
> param is set to 123 when abc is linked to the kernel.

You would put something like

abc.param="123" in loader.conf or add it via kenv, and then in your
variable declaration area:

static int myparam = 0;
TUNABLE_INT("abc.param", &myparam);

That works for a module that can only be loaded once, and a static
tuneable name. If you don't know the name of the tunable until your
driver is loaded, you can use the TUNABLE_INT_FETCH() macro in a
function. Sysctls are recommended if you have a value that can be
changed after the module is loaded.

If you are writing a device driver, take a look at how if_fxp.c pulls
in per-device tunable/sysctls (search for bundle_max).

-- 
Dan Nelson
dnelson at allantgroup.com
_______________________________________________
freebsd-questions at freebsd.org mailing list
http://lists.freebsd.org/mailman/listinfo/freebsd-questions
To unsubscribe, send any mail to "freebsd-questions-unsubscribe at freebsd.org"



---------------------------------
Do You Yahoo!?
×¢²áÊÀ½çÒ»Á÷Æ·ÖʵÄÑÅ»¢Ãâ·ÑµçÓÊ