Re: MacBook users: possible fix for the SMP problem

I'm requesting review for the following patch:

Index: sys/i386/isa/clock.c
===================================================================
RCS file: /home/ncvs/src/sys/i386/isa/clock.c,v
retrieving revision 1.240
diff -u -p -r1.240 clock.c
--- sys/i386/isa/clock.c	26 Oct 2007 03:23:54 -0000	1.240
+++ sys/i386/isa/clock.c	7 Nov 2007 15:27:21 -0000
_at__at_ -130,6 +130,9 _at__at_ static	u_char	rtc_statusb = RTCSB_24HR;
  #define	ACQUIRED	2
  #define	ACQUIRE_PENDING	3

+/* Intel ICH register */
+#define ICH_PMBASE	0x400
+
  static	u_char	timer2_state;

  static	unsigned i8254_get_timecount(struct timecounter *tc);
_at__at_ -616,11 +619,26 _at__at_ i8254_init(void)
  void
  startrtclock()
  {
+	char *ichenv;
  	u_int delta, freq;

  	writertc(RTC_STATUSA, rtc_statusa);
  	writertc(RTC_STATUSB, RTCSB_24HR);

+	/*
+	 * On some systems, namely MacBooks, we need to disallow the
+	 * legacy USB circuit to generate an SMI# because this can
+	 * cause several problems, namely: incorrect CPU frequency
+	 * detection and failure to start the APs.
+	 */
+	ichenv = getenv("hw.ich.disable_legacy_usb");
+	if (ichenv !=  NULL) {
+		if (bootverbose)
+			printf("Disabling LEGACY_USB_EN bit on Intel ICH.\n");
+		outl(ICH_PMBASE + 0x30, inl(ICH_PMBASE + 0x30) & ~0x8);
+		freeenv(ichsmi);
+	}
+	
  	freq = calibrate_clocks();
  #ifdef CLK_CALIBRATION_LOOP
  	if (bootverbose) {


If you have a MacBook, you now need to set hw.ich.disable_legacy_usb  
on the boot loader prompt or in loader.conf. I decided to go this  
route because it seems safer. Imagine the case where there's a port at  
the same IO address that has nothing to do with the ICH7. If we tried  
to issue the outl() on every system, something bad could happen.

Comments?

Regards.
--
Rui Paulo