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Date:      Wed, 02 Dec 1998 17:07:00 -0800
From:      Mike Smith <mike@smith.net.au>
To:        David Dawes <dawes@rf900.physics.usyd.edu.au>
Cc:        Peter Jeremy <peter.jeremy@auss2.alcatel.com.au>, mike@smith.net.au, current@FreeBSD.ORG
Subject:   Re: sio breakage 
Message-ID:  <199812030107.RAA01213@dingo.cdrom.com>
In-Reply-To: Your message of "Thu, 03 Dec 1998 11:52:22 %2B1100." <19981203115222.A3051@rf900.physics.usyd.edu.au> 

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> On Wed, Dec 02, 1998 at 08:46:45PM +1100, Peter Jeremy wrote:
> 
> >>> I don't believe this is reasonable.  We should provide some safe way
> >>> for an application program to execute code with interrupts disabled.
> >>> Amongst other applications, XFree86 needs this.
> >>
> >>It shouldn't (ideally).
> >I agree.  And whilst I haven't checked why, XFree86 does appear to
> >disable interrupts at times.
> 
> I agree too, but it does disable interrupts when probing for fixed pixel
> clocks (which is mostly only done for obsolete hardware), and sometimes
> when programming PLLs.  If someone has a better way of handling time
> critical thing like this (preferably in a portable way), please let me
> know.  I'd love to dump our disable interrupt code.

I get the impression from this though that you only do interrupt 
disables when probing or changing video modes, is that correct?

The entire train of angst here is descended from percieved problems in 
interrupt delivery during normal operation; if you're only disabling 
interrupts during startup then this prettymuch exonerates the X server.

> >>  If it does, this is clearly indicative of a
> >>need to move some of the server code into the kernel,
> >You mean, like GGI <http://www.ggi-project.org/>; :-).
> 
> There are some tasks that are much better suited to the kernel, and
> perhaps a better balance could be found by just doing those few selected
> things in the kernel and leaving the rest of it in user space.

Quite possibly; I wasn't sure that it would help performance, and it 
would *certainly* make your lives harder.  8(

-- 
\\  Sometimes you're ahead,       \\  Mike Smith
\\  sometimes you're behind.      \\  mike@smith.net.au
\\  The race is long, and in the  \\  msmith@freebsd.org
\\  end it's only with yourself.  \\  msmith@cdrom.com



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