Date: Sat, 9 Aug 2008 21:43:05 +1000 From: Peter Jeremy <peterjeremy@optushome.com.au> To: Robert Watson <rwatson@freebsd.org> Cc: src-committers@freebsd.org, John Baldwin <jhb@freebsd.org>, cvs-src@freebsd.org, Ed Schouten <ed@freebsd.org>, cvs-all@freebsd.org, Kostik Belousov <kostikbel@gmail.com> Subject: Re: cvs commit: src/sys/dev/io iodev.c Message-ID: <20080809114305.GV64458@server.vk2pj.dyndns.org> In-Reply-To: <alpine.BSF.1.10.0808091207350.16028@fledge.watson.org> References: <200808081343.m78DhwYE068477@repoman.freebsd.org> <200808081226.32089.jhb@freebsd.org> <20080809001256.GL64458@server.vk2pj.dyndns.org> <alpine.BSF.1.10.0808091127170.36489@fledge.watson.org> <20080809103338.GN97161@deviant.kiev.zoral.com.ua> <alpine.BSF.1.10.0808091207350.16028@fledge.watson.org>
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On 2008-Aug-09 12:08:42 +0100, Robert Watson <rwatson@freebsd.org> wrote:
>While /dev/io appeals to the UNIX "everything is a file" sensibility, I th=
ink=20
>the system calls we have for this on i386 are more conceptually coherent.
IMO, /dev/io is inherently a kludge - it's really more a MAC issue
than anything like a file. Whilst you get a FD by opening /dev/io,
you never use that FD for anything other than passing to close(2).
Instead, you are using a magic side-effect that allows you to execute
'in' and 'out' instructions whilst you hold that FD open. AFAIK, the
sole reason for having it appear as a file is that (in the absence of
a MAC framework), the filesystem provides the only mechanism for
access control. IMHO, /dev/io should be deprecated in favour of
something like the MAC framework. (Note that i386_{g,s}et_ioperm(2)
are nor suitable in their current form because there is no mechanism
for the system administrator to define access controls).
--=20
Peter Jeremy
Please excuse any delays as the result of my ISP's inability to implement
an MTA that is either RFC2821-compliant or matches their claimed behaviour.
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