cvs commit: src/sys/amd64/amd64 machdep.c

[John Baldwin]

On Monday 28 November 2005 04:51 pm, Scott Long wrote:
> John Baldwin wrote:
> > On Monday 28 November 2005 04:06 pm, Scott Long wrote:
> >>John Baldwin wrote:
> >>>On Monday 21 November 2005 01:39 pm, John Baldwin wrote:
> >>>>jhb         2005-11-21 18:39:17 UTC
> >>>>
> >>>> FreeBSD src repository
> >>>>
> >>>> Modified files:
> >>>>   sys/amd64/amd64      machdep.c
> >>>> Log:
> >>>> Expand the hack to mask the atpics if 'device atpic' is not in the
> >>>>kernel during boot up.  Now we do a full reset of the 8259As and setup
> >>>> a simple interrupt handler (we actually borrow the apic one that just
> >>>> does an immediate iret) to handle any spurious interrupts triggered by
> >>>> either chip. This should fix some folks that were getting a Trap 30
> >>>> during bootup of certain SMP AMD systems.  This might get pushed into
> >>>> the 6.0 branch as an errata.  For now a suitable workaround is to add
> >>>> 'device atpic' to your kernel config.
> >>>>
> >>>> Tested by:      scottl
> >>>> Helpful info from:      dillon
> >>>> MFC after:      1 week
> >>>
> >>>Hmm, we probably still need to reprogram the ATPIC on resume as well.
> >>>I'm not sure it's actually worth not just compiling the atpic code in on
> >>>amd64.
> >>
> >>Problems aside, what are the benefits to not having the atpic
> >>unconditionally included on amd64?
> >
> > Purely space savings.  It's whatever the size of atpic.o, elcr.o, and the
> > bits of atpic_vector.S that make it into exception.o are.
>
> Ok, so it doesn't cut down on runtime overhead?  The file sizes look to
> be:
>
> atpic.o     15k
> elcr.o      2.5k
> exception.o 200byte delta

No, there isn't any effect on runtime.

> If, down the road, a motherboard shows up without an atpic or one that
> is horribly broken, would we be worse off for having the atpic code in
> there?

Well, both i386 and amd64 assume an atpic is there.  Even if you don't include 
'device atpic' on amd64, we do the manual bit banging to the I/O ports that 
assume it is there in the code I just changed.

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