MacBook users: possible fix for the SMP problem

Scott Long scottl at
Mon Nov 5 10:18:21 PST 2007

Rui Paulo wrote:
> On Nov 4, 2007 11:14 PM, Rink Springer <rink at> wrote:
>> Hi Rui,
>> On Sun, Nov 04, 2007 at 08:59:28PM +0000, Rui Paulo wrote:
>>> Note: this is still a hack. I'm still thinking about a way to
>>> correctly identify on which systems we need to apply this fix.
>> This indeed looks hackikly - I don't know whether it's possible to
>> distinguish between a 'normal' PC or a MacBook - but if this is not
>> possible, maybe a kernel option is in order?
> It's possible to distinguish between a MacBook and a PeeCee via smbios
> vendor strings.
> But what I actually wanted was something more general.
> Regards.

Turning this on universally should only affect USB keyboard operation in
KDB early in boot (or if the USB drivers were omitted during boot).  It
sounds like this affects clock calibration on other systems, not just
Macs.  So I'd vote for this being made into a negative option, i.e.


That'll at least let people boot with a GENERIC kernel and then decide
for themselves if they want it enabled or disabled.  It could also be
made into tunable and set via the loader menu, but I'd only advocate
that if there were found to be other side effects that prevented some
users from booting with GENERIC.

Anyways, good job figuring this out.  Talk about an obscure problem.
Now I don't feel so bad about spending days in vain going line-by-line
through the AP startup code looking for the problem.


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