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List:       freebsd-hackers
Subject:    Re: reserved/local ioctl values?
From:       Mike Smith <mike () smith ! net ! au>
Date:       1999-07-30 8:05:52
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> I'l looking at defining about a dozen ioctl calls for a local device driver. 
> When looking at the _IO, _IO, _IOW, _IOR, and _IOWR macros, I'm interested if
> there are any "reserved" or "local" values for the first parameter? 

Not really, as such. 

> In short, I'd hate to use a seemly unused value, just to suddenly be in
> conflict with a major set of ioctls (particularly terminal, as this is the
> type of driver it will be). Also, would it be wise to reuse an existing value?

If you want to add private ioctls to a given subsystem, either pick an 
arbitrarily high function number, or another letter that's not commonly 
associated with that subsystem.  Eg. I would probably pick 'z' if I 
were going to add a local ioctl to the tty subsystem.

-- 
\\  The mind's the standard       \\  Mike Smith
\\  of the man.                   \\  msmith@freebsd.org
\\    -- Joseph Merrick           \\  msmith@cdrom.com




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