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Date:      Wed, 29 Mar 2006 13:15:54 -0500
From:      John Baldwin <jhb@freebsd.org>
To:        Scott Long <scottl@samsco.org>
Cc:        Bruce M Simpson <bms@spc.org>, "Conrad J. Sabatier" <conrads@cox.net>, freebsd-current@freebsd.org
Subject:   Re: device atpic to be deprecated?
Message-ID:  <200603291315.56671.jhb@freebsd.org>
In-Reply-To: <442ABF1B.5040305@samsco.org>
References:  <20060329020527.f8f087a4.conrads@cox.net> <200603291157.54467.jhb@freebsd.org> <442ABF1B.5040305@samsco.org>

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On Wednesday 29 March 2006 12:08, Scott Long wrote:
> John Baldwin wrote:
> > On Wednesday 29 March 2006 11:26, Scott Long wrote:
> > 
> >>John Baldwin wrote:
> >>
> >>>On Wednesday 29 March 2006 03:51 am, Bruce M Simpson wrote:
> >>>
> >>>
> >>>>On Wed, Mar 29, 2006 at 02:05:27AM -0600, Conrad J. Sabatier wrote:
> >>>>
> >>>>
> >>>>>Is the plan still in effect to abolish this device?
> >>>>
> >>>>To my mind it wouldn't make much sense, given the sheer amount of hardware
> >>>>out there which doesn't have an IOAPIC, then again I'm probably out of
> >>>>touch with the state of interrupt handling in -CURRENT.
> >>>
> >>>
> >>>All amd64 machines (which is where atpic would be removed) have an APIC.
> >>>
> >>
> >>That's kind of like saying that ISA will be removed because there is PCI
> >>=-)  Having an APIC doesn't necessarily guarantee that it works.  There
> >>have been enough reports of problems on the mailing lists over time that
> >>I think it's a bit premature to declare the ATPIC dead.  Also, is the
> >>ATPIC code in amd64 causing problems, holding back progress, or creating
> >>a maintenance burden?
> > 
> > 
> > I think that once the lapic timer stuff was added almost all of the APIC
> > issues I was aware of went away on amd64 that were fixed by using device
> > atpic instead.  Most of the earlier problems were due to chipsets not
> > setting up pin 0 as extint, etc. but all that is no longer relevant when
> > we switched to using the lapic timer and stopped using irq0 and irq8 with
> > APIC.  This is the first I've heard since the lapic timer stuff that APIC
> > didn't work on an amd64 box, and device atpic has been off by default in
> > HEAD for quite a while now.  If we were able to require APIC on amd64, then
> > we might be able to try out some optimizations and other things I haven't
> > bothered with since they wouldn't be feasible on i386.
> > 
> 
> Fine, remove it.

I have to make sure it really works for everyone first though before
removing it would really be viable. :-/

-- 
John Baldwin <jhb@FreeBSD.org>  <><  http://www.FreeBSD.org/~jhb/
"Power Users Use the Power to Serve"  =  http://www.FreeBSD.org



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