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Date: Thu, 11 Aug 2005 01:50:44 +0400
From: Sergey Uvarov <uvarovsl@mail.pnpi.spb.ru>
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To: John Baldwin <jhb@freebsd.org>
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Cc: freebsd-hackers@freebsd.org
Subject: Re: preferable way to control kernel module
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>>>>I'm writing a kernel module for my own needs. AFAIK the following
>>>>methods could be used:
>>>>
>>>>1) allocate not used system call with help of SYSCALL_MODULE macro
>>>>
>>>>2) allocate proprieatry oid via SYSCTL_OID(OID_AUTO) and write an
>>>>appropriate sysctl handler(s)
>>>>
>>>>3) add a file in /dev and use ioctl(2) call
>>>>
>>>>What is a preferable way to control my module?
>>>
>>>It depends on what you want to do really.  I've used sysctl's for simple
>>>debug modules where I write to the sysctl to have it perform a desired
>>>action.
>>
>>I need to pass some configuration parameters to my module and retrieve a
>>status back. Interface is quite similar to ptrace(2) syscall. I don't
>>need to pass large amount of data.
> 
> 
> If it's a single integer or some such, I'd say use sysctl.  If it's a 
> structure, I'd go the ioctl(2) route.  Creating /dev entries isn't all that 
> hard.  In your case you'd just need open/close/ioctl in a cdevsw, then use 
> make_dev() during MOD_LOAD and destroy_dev() during MOD_UNLOAD.
> 

Thank you for advise. But I wonder: what is wrong with syscall approach 
(via SYSCALL_MODULE macro)?

Thanks again,
	Sergey.