Hi,

On 11/3/07, Marco Trillo <marcotrillo@gmail.com> wrote:
> I have collected more information about the issue: I found a Linux
> bugreport of a similar problem (APIC timing calibration problem) which
> contained a possible cause: some feature of the Intel ICH7 called
> "LEGACY_USB" which "causes legacy USB circuit to cause SMI";
> apparently such SMIs in the middle of the calibration process botch
> it.
>
> Based on such report, I have added a quirk at the start of the
> initrtclock() function in src/sys/arch/x86/isa/clock.c to disable the
> LEGACY_USB SMI bit:
>
> outl(0x430, inl(0x430) & ~8);
>
> Indeed, the quirk appears to be working:

More news about the issue: as I reported before, that patch indeed
appears to resolve all the issues (thanks to Ryan Lortie for finding
the cause of the problem).
The problem is that adding this line to a generic kernel is quirky and
may affect negatively to other (non-MacBook) systems.

There was some discussion on FreeBSD lists about how to implement this
in a portable and clean way. It seems that the MacBook can be detected
using a SMBIOS 'system product' string:
<http://lists.freebsd.org/pipermail/freebsd-current/2007-November/079643.html>.

What do you think of applying a similar patch to NetBSD?

By the way, I sent a PR describing the issue and the fix as "port-i386/37305".

Thanks,
Marco