Using inb() and outb()

Robert Bonomi bonomi at
Wed May 23 02:52:05 UTC 2012

> From owner-freebsd-questions at  Tue May 22 21:30:21 2012
> Date: Tue, 22 May 2012 19:27:44 -0700
> From: "Thomas D. Dean" <tomdean at>
> To: freebsd-questions at
> Subject: Re: Using inb() and outb()
> On 05/22/12 17:09, Eitan Adler wrote:
> > On 22 May 2012 14:25, Thomas D. Dean<tomdean at>  wrote:
> >> On 05/22/12 14:08, Robert Bonomi wrote:
> >>
> >> That is what I thought.
> >>
> >> The entire operation will have to run as root.  Nothing will be non-root.
> >
> > Can you make a SUID helper which only does the inb/outb operations as root?
> >
> I am planing to move the higher level functions to a driver.
> I really want a userland interface to the process.

It just occured to me -- you could do a 'daemon' process that ran as the
superuser, and provided the hardware-level services to a non-root client
via, say,  RPC, or a bare 'socket' ('unix' or 'ip') connection.

Doing the I/O via RPC would be 'interesting', in that the 'device' could
be physically connected to one machine (almost an 'embedded'-class  micro-
controller), while the vast majority of the 'control progrm' could run on
an entirely different machine.

If you're up to doing the device-driver coding, it is a =better= solution,
because then you can use the filesystem access-control mechanisms to limit
access to the 'device'. 

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