Use the local APIC timer to drive the various kernel clocks on SMP machines

rather than forwarding interrupts from the clock devices around using IPIs:
- Add an IDT vector that pushes a clock frame and calls
  lapic_handle_timer().
- Add functions to program the local APIC timer including setting the
  divisor, and setting up the timer to either down a periodic countdown
  or one-shot countdown.
- Add a lapic_setup_clock() function that the BSP calls from
  cpu_init_clocks() to setup the local APIC timer if it is going to be
  used.  The setup uses a one-shot countdown to calibrate the timer.  We
  then program the timer on each CPU to fire at a frequency of hz * 3.
  stathz is defined as freq / 23 (hz * 3 / 23), and profhz is defined as
  freq / 2 (hz * 3 / 2).  This gives the clocks relatively prime divisors
  while keeping a low LCM for the frequency of the clock interrupts.
  Thanks to Peter Jeremy for suggesting this approach.
- Remove the hardclock and statclock forwarding code including the two
  associated IPIs.  The bitmap IPI handler has now effectively degenerated
  to just IPI_AST.
- When the local APIC timer is used we don't turn the RTC on at all, but
  we still enable interrupts on the ISA timer 0 (i8254) for timecounting
  purposes.

2 files changed, 4 insertions, 6 deletions

diff --git a/sys/i386/include/apicvar.h b/sys/i386/include/apicvar.h
index a0f06ba..d4af36b 100644
--- a/sys/i386/include/apicvar.h
+++ b/sys/i386/include/apicvar.h
@@ -122,9 +122,7 @@
 
 /* IPIs handled by IPI_BITMAPED_VECTOR  (XXX ups is there a better place?) */
 #define	IPI_AST		0 	/* Generate software trap. */
-#define	IPI_HARDCLOCK	1	/* Inter-CPU clock handling. */
-#define	IPI_STATCLOCK	2
-#define IPI_BITMAP_LAST IPI_STATCLOCK
+#define IPI_BITMAP_LAST IPI_AST
 #define IPI_IS_BITMAPED(x) ((x) <= IPI_BITMAP_LAST)
 
 #define	IPI_STOP	(APIC_IPI_INTS + 6)	/* Stop CPU until restarted. */
@@ -171,7 +169,7 @@ struct apic_enumerator {
 inthand_t
 	IDTVEC(apic_isr1), IDTVEC(apic_isr2), IDTVEC(apic_isr3),
 	IDTVEC(apic_isr4), IDTVEC(apic_isr5), IDTVEC(apic_isr6),
-	IDTVEC(apic_isr7), IDTVEC(spuriousint);
+	IDTVEC(apic_isr7), IDTVEC(spuriousint), IDTVEC(timerint);
 
 u_int	apic_irq_to_idt(u_int irq);
 u_int	apic_idt_to_irq(u_int vector);
@@ -202,6 +200,7 @@ void	lapic_ipi_raw(register_t icrlo, u_int dest);
 void	lapic_ipi_vectored(u_int vector, int dest);
 int	lapic_ipi_wait(int delay);
 void	lapic_handle_intr(struct intrframe frame);
+void	lapic_handle_timer(struct clockframe frame);
 void	lapic_set_logical_id(u_int apic_id, u_int cluster, u_int cluster_id);
 int	lapic_set_lvt_mask(u_int apic_id, u_int lvt, u_char masked);
 int	lapic_set_lvt_mode(u_int apic_id, u_int lvt, u_int32_t mode);
@@ -211,6 +210,7 @@ int	lapic_set_lvt_triggermode(u_int apic_id, u_int lvt,
 	    enum intr_trigger trigger);
 void	lapic_set_tpr(u_int vector);
 void	lapic_setup(void);
+int	lapic_setup_clock(void);
 
 #endif /* !LOCORE */
 #endif /* _MACHINE_APICVAR_H_ */
diff --git a/sys/i386/include/smp.h b/sys/i386/include/smp.h
index 6bad810a..7837120 100644
--- a/sys/i386/include/smp.h
+++ b/sys/i386/include/smp.h
@@ -67,8 +67,6 @@ void	ipi_selected(u_int cpus, u_int ipi);
 void	ipi_all(u_int ipi);
 void	ipi_all_but_self(u_int ipi);
 void	ipi_self(u_int ipi);
-void	forward_statclock(void);
-void	forward_hardclock(void);
 void 	ipi_bitmap_handler(struct clockframe frame);
 u_int	mp_bootaddress(u_int);
 int	mp_grab_cpu_hlt(void);