PERFORCE change 85514 for review

Robert Watson rwatson at FreeBSD.org
Wed Oct 19 04:30:52 PDT 2005


On Tue, 18 Oct 2005, John Baldwin wrote:

> http://perforce.freebsd.org/chv.cgi?CH=85514
>
> Change 85514 by jhb at jhb_slimer on 2005/10/18 20:03:00
>
> 	Rework KDB_STOP_NMI some to make it less KDB-specific.
> 	- Use stoppcbs[] on i386 and amd64 always, regardless of KDB_STOP_NMI.
> 	- Rename KDB_STOP_NMI to STOP_NMI and have it apply to any IPI_STOP
> 	  ipi.
> 	- Fix ipi_all(), ipi_all_but_self(), and ipi_self() to correctly
> 	  handle bitmapped IPIs and STOP_NMI.

Wouldn't it make sense to simply always use an NMI when entering the 
debugger on SMP?  I guess there are some potential races in simultaneous 
or nearly simultaneous entry of the debugger from multiple CPUs at once, 
but it seems lately I've been bumping into a moderate number of cases 
where the CPUs stack up and wedge during SMP debugger entry, possibly due 
to the CPU entering the debugger holding a spinlock.

Robert N M Watson

>
> Affected files ...
>
> .. //depot/projects/smpng/sys/amd64/amd64/mp_machdep.c#26 edit
> .. //depot/projects/smpng/sys/amd64/amd64/trap.c#36 edit
> .. //depot/projects/smpng/sys/amd64/conf/NOTES#22 edit
> .. //depot/projects/smpng/sys/amd64/include/smp.h#9 edit
> .. //depot/projects/smpng/sys/conf/options.amd64#14 edit
> .. //depot/projects/smpng/sys/conf/options.i386#50 edit
> .. //depot/projects/smpng/sys/conf/options.pc98#49 edit
> .. //depot/projects/smpng/sys/i386/conf/NOTES#108 edit
> .. //depot/projects/smpng/sys/i386/i386/mp_machdep.c#91 edit
> .. //depot/projects/smpng/sys/i386/i386/trap.c#86 edit
> .. //depot/projects/smpng/sys/i386/include/smp.h#17 edit
> .. //depot/projects/smpng/sys/kern/subr_kdb.c#12 edit
> .. //depot/projects/smpng/sys/kern/subr_smp.c#42 edit
> .. //depot/projects/smpng/sys/notes#61 edit
> .. //depot/projects/smpng/sys/pc98/conf/NOTES#45 edit
> .. //depot/projects/smpng/sys/sys/smp.h#15 edit
>
> Differences ...
>
> ==== //depot/projects/smpng/sys/amd64/amd64/mp_machdep.c#26 (text+ko) ====
>
> @@ -28,7 +28,6 @@
> __FBSDID("$FreeBSD: src/sys/amd64/amd64/mp_machdep.c,v 1.262 2005/08/19 22:10:19 pjd Exp $");
>
> #include "opt_cpu.h"
> -#include "opt_kdb.h"
> #include "opt_kstack_pages.h"
> #include "opt_mp_watchdog.h"
> #include "opt_sched.h"
> @@ -113,10 +112,30 @@
>
> extern inthand_t IDTVEC(fast_syscall), IDTVEC(fast_syscall32);
>
> +#ifdef STOP_NMI
> +volatile cpumask_t ipi_nmi_pending;
> +
> +static void	ipi_nmi_selected(u_int32_t cpus);
> +#endif
> +
> /*
>  * Local data and functions.
>  */
>
> +#ifdef STOP_NMI
> +/*
> + * Provide an alternate method of stopping other CPUs. If another CPU has
> + * disabled interrupts the conventional STOP IPI will be blocked. This
> + * NMI-based stop should get through in that case.
> + */
> +static int stop_cpus_with_nmi = 1;
> +SYSCTL_INT(_debug, OID_AUTO, stop_cpus_with_nmi, CTLTYPE_INT | CTLFLAG_RW,
> +    &stop_cpus_with_nmi, 0, "");
> +TUNABLE_INT("debug.stop_cpus_with_nmi", &stop_cpus_with_nmi);
> +#else
> +#define	stop_cpus_with_nmi	0
> +#endif
> +
> static u_int logical_cpus;
>
> /* used to hold the AP's until we are ready to release them */
> @@ -199,11 +218,6 @@
> 	smp_topology = &mp_top;
> }
>
> -
> -#ifdef KDB_STOP_NMI
> -volatile cpumask_t ipi_nmi_pending;
> -#endif
> -
> /*
>  * Calculate usable address in base memory for AP trampoline code.
>  */
> @@ -945,6 +959,12 @@
> 		ipi = IPI_BITMAP_VECTOR;
> 	}
>
> +#ifdef STOP_NMI
> +	if (ipi == IPI_STOP && stop_cpus_with_nmi) {
> +		ipi_nmi_selected(cpus);
> +		return;
> +	}
> +#endif
> 	CTR3(KTR_SMP, "%s: cpus: %x ipi: %x", __func__, cpus, ipi);
> 	while ((cpu = ffs(cpus)) != 0) {
> 		cpu--;
> @@ -975,6 +995,10 @@
> ipi_all(u_int ipi)
> {
>
> +	if (IPI_IS_BITMAPED(ipi) || (ipi == IPI_STOP && stop_cpus_with_nmi)) {
> +		ipi_selected(all_cpus, ipi);
> +		return;
> +	}
> 	CTR2(KTR_SMP, "%s: ipi: %x", __func__, ipi);
> 	lapic_ipi_vectored(ipi, APIC_IPI_DEST_ALL);
> }
> @@ -986,6 +1010,10 @@
> ipi_all_but_self(u_int ipi)
> {
>
> +	if (IPI_IS_BITMAPED(ipi) || (ipi == IPI_STOP && stop_cpus_with_nmi)) {
> +		ipi_selected(PCPU_GET(other_cpus), ipi);
> +		return;
> +	}
> 	CTR2(KTR_SMP, "%s: ipi: %x", __func__, ipi);
> 	lapic_ipi_vectored(ipi, APIC_IPI_DEST_OTHERS);
> }
> @@ -997,11 +1025,15 @@
> ipi_self(u_int ipi)
> {
>
> +	if (IPI_IS_BITMAPED(ipi) || (ipi == IPI_STOP && stop_cpus_with_nmi)) {
> +		ipi_selected(PCPU_GET(cpumask), ipi);
> +		return;
> +	}
> 	CTR2(KTR_SMP, "%s: ipi: %x", __func__, ipi);
> 	lapic_ipi_vectored(ipi, APIC_IPI_DEST_SELF);
> }
>
> -#ifdef KDB_STOP_NMI
> +#ifdef STOP_NMI
> /*
>  * send NMI IPI to selected CPUs
>  */
> @@ -1011,7 +1043,6 @@
> void
> ipi_nmi_selected(u_int32_t cpus)
> {
> -
> 	int cpu;
> 	register_t icrlo;
>
> @@ -1020,10 +1051,8 @@
>
> 	CTR2(KTR_SMP, "%s: cpus: %x nmi", __func__, cpus);
>
> -
> 	atomic_set_int(&ipi_nmi_pending, cpus);
>
> -
> 	while ((cpu = ffs(cpus)) != 0) {
> 		cpu--;
> 		cpus &= ~(1 << cpu);
> @@ -1035,43 +1064,43 @@
> 		if (!lapic_ipi_wait(BEFORE_SPIN))
> 			panic("ipi_nmi_selected: previous IPI has not cleared");
>
> -		lapic_ipi_raw(icrlo,cpu_apic_ids[cpu]);
> +		lapic_ipi_raw(icrlo, cpu_apic_ids[cpu]);
> 	}
> }
>
> -
> int
> ipi_nmi_handler()
> {
> -	int cpu  = PCPU_GET(cpuid);
> -	void *restartfunc(void);
> +	int cpu = PCPU_GET(cpuid);
> +	int cpumask = PCPU_GET(cpumask);
> +	void (*restartfunc)(void);
>
> -	if(!(atomic_load_acq_int(&ipi_nmi_pending) & (1 << cpu)))
> +	if (!(ipi_nmi_pending & cpumask))
> 		return 1;
>
> -	atomic_clear_int(&ipi_nmi_pending,1 << cpu);
> +	atomic_clear_int(&ipi_nmi_pending, cpumask);
>
> 	savectx(&stoppcbs[cpu]);
>
> 	/* Indicate that we are stopped */
> -	atomic_set_int(&stopped_cpus,1 << cpu);
> -
> +	atomic_set_int(&stopped_cpus, cpumask);
>
> 	/* Wait for restart */
> -	while(!(atomic_load_acq_int(&started_cpus) & (1 << cpu)))
> +	while (!(started_cpus & cpumask))
> 	    ia32_pause();
>
> -	atomic_clear_int(&started_cpus,1 << cpu);
> -	atomic_clear_int(&stopped_cpus,1 << cpu);
> +	atomic_clear_int(&started_cpus, cpumask);
> +	atomic_clear_int(&stopped_cpus, cpumask);
>
> -	restartfunc = (void (*)(void))atomic_readandclear_long(&cpustop_restartfunc);
> +	restartfunc = (void (*)(void))atomic_readandclear_long(
> +		(u_long *)&cpustop_restartfunc);
> 	if (restartfunc != NULL)
> 		restartfunc();
>
> 	return 0;
> }
>
> -#endif /* KDB_STOP_NMI */
> +#endif /* STOP_NMI */
>
> /*
>  * This is called once the rest of the system is up and running and we're
>
> ==== //depot/projects/smpng/sys/amd64/amd64/trap.c#36 (text+ko) ====
>
> @@ -167,13 +167,13 @@
> 	PCPU_LAZY_INC(cnt.v_trap);
> 	type = frame.tf_trapno;
>
> -#ifdef KDB_STOP_NMI
> -	/* Handler for NMI IPIs used for debugging */
> +#ifdef STOP_NMI
> +	/* Handler for NMI IPIs used for stopping CPUs. */
> 	if (type == T_NMI) {
> 	         if (ipi_nmi_handler() == 0)
> 	                   goto out;
> 	}
> -#endif /* KDB_STOP_NMI */
> +#endif /* STOP_NMI */
>
> #ifdef KDB
> 	if (kdb_active) {
>
> ==== //depot/projects/smpng/sys/amd64/conf/NOTES#22 (text+ko) ====
>
> @@ -39,7 +39,7 @@
> #
> # Debugging options.
> #
> -options		KDB_STOP_NMI		# Stop CPUS using NMI instead of IPI
> +options		STOP_NMI		# Stop CPUS using NMI instead of IPI
>
>
>
>
> ==== //depot/projects/smpng/sys/amd64/include/smp.h#9 (text+ko) ====
>
> @@ -63,9 +63,8 @@
> void	smp_invltlb(void);
> void	smp_masked_invltlb(u_int mask);
>
> -#ifdef KDB_STOP_NMI
> -int ipi_nmi_handler(void);
> -void ipi_nmi_selected(u_int32_t cpus);
> +#ifdef STOP_NMI
> +int	ipi_nmi_handler(void);
> #endif
>
> #endif /* !LOCORE */
>
> ==== //depot/projects/smpng/sys/conf/options.amd64#14 (text+ko) ====
>
> @@ -57,4 +57,4 @@
> DEV_ATPIC		opt_atpic.h
>
> # Debugging
> -KDB_STOP_NMI		opt_kdb.h
> +STOP_NMI		opt_cpu.h
>
> ==== //depot/projects/smpng/sys/conf/options.i386#50 (text+ko) ====
>
> @@ -161,5 +161,5 @@
> ASR_COMPAT		opt_asr.h
>
> # Debugging
> -KDB_STOP_NMI		opt_kdb.h
> +STOP_NMI		opt_cpu.h
> NPX_DEBUG		opt_npx.h
>
> ==== //depot/projects/smpng/sys/conf/options.pc98#49 (text+ko) ====
>
> @@ -103,5 +103,5 @@
> DEV_NPX			opt_npx.h
>
> # Debugging
> -KDB_STOP_NMI		opt_kdb.h
> +STOP_NMI		opt_cpu.h
> NPX_DEBUG		opt_npx.h
>
> ==== //depot/projects/smpng/sys/i386/conf/NOTES#108 (text+ko) ====
>
> @@ -56,7 +56,7 @@
>
> # Debugging options.
> #
> -options		KDB_STOP_NMI		# Stop CPUS using NMI instead of IPI
> +options		STOP_NMI		# Stop CPUS using NMI instead of IPI
>
>
>
>
> ==== //depot/projects/smpng/sys/i386/i386/mp_machdep.c#91 (text+ko) ====
>
> @@ -28,7 +28,6 @@
>
> #include "opt_apic.h"
> #include "opt_cpu.h"
> -#include "opt_kdb.h"
> #include "opt_kstack_pages.h"
> #include "opt_mp_watchdog.h"
> #include "opt_sched.h"
> @@ -177,8 +176,10 @@
> vm_offset_t smp_tlb_addr2;
> volatile int smp_tlb_wait;
>
> -#ifdef KDB_STOP_NMI
> +#ifdef STOP_NMI
> volatile cpumask_t ipi_nmi_pending;
> +
> +static void	ipi_nmi_selected(u_int32_t cpus);
> #endif
>
> #ifdef COUNT_IPIS
> @@ -198,6 +199,20 @@
>  * Local data and functions.
>  */
>
> +#ifdef STOP_NMI
> +/*
> + * Provide an alternate method of stopping other CPUs. If another CPU has
> + * disabled interrupts the conventional STOP IPI will be blocked. This
> + * NMI-based stop should get through in that case.
> + */
> +static int stop_cpus_with_nmi = 1;
> +SYSCTL_INT(_debug, OID_AUTO, stop_cpus_with_nmi, CTLTYPE_INT | CTLFLAG_RW,
> +    &stop_cpus_with_nmi, 0, "");
> +TUNABLE_INT("debug.stop_cpus_with_nmi", &stop_cpus_with_nmi);
> +#else
> +#define	stop_cpus_with_nmi	0
> +#endif
> +
> static u_int logical_cpus;
>
> /* used to hold the AP's until we are ready to release them */
> @@ -1186,6 +1201,12 @@
> 		ipi = IPI_BITMAP_VECTOR;
> 	}
>
> +#ifdef STOP_NMI
> +	if (ipi == IPI_STOP && stop_cpus_with_nmi) {
> +		ipi_nmi_selected(cpus);
> +		return;
> +	}
> +#endif
> 	CTR3(KTR_SMP, "%s: cpus: %x ipi: %x", __func__, cpus, ipi);
> 	while ((cpu = ffs(cpus)) != 0) {
> 		cpu--;
> @@ -1216,6 +1237,10 @@
> ipi_all(u_int ipi)
> {
>
> +	if (IPI_IS_BITMAPED(ipi) || (ipi == IPI_STOP && stop_cpus_with_nmi)) {
> +		ipi_selected(all_cpus, ipi);
> +		return;
> +	}
> 	CTR2(KTR_SMP, "%s: ipi: %x", __func__, ipi);
> 	lapic_ipi_vectored(ipi, APIC_IPI_DEST_ALL);
> }
> @@ -1227,6 +1252,10 @@
> ipi_all_but_self(u_int ipi)
> {
>
> +	if (IPI_IS_BITMAPED(ipi) || (ipi == IPI_STOP && stop_cpus_with_nmi)) {
> +		ipi_selected(PCPU_GET(other_cpus), ipi);
> +		return;
> +	}
> 	CTR2(KTR_SMP, "%s: ipi: %x", __func__, ipi);
> 	lapic_ipi_vectored(ipi, APIC_IPI_DEST_OTHERS);
> }
> @@ -1238,11 +1267,15 @@
> ipi_self(u_int ipi)
> {
>
> +	if (IPI_IS_BITMAPED(ipi) || (ipi == IPI_STOP && stop_cpus_with_nmi)) {
> +		ipi_selected(PCPU_GET(cpumask), ipi);
> +		return;
> +	}
> 	CTR2(KTR_SMP, "%s: ipi: %x", __func__, ipi);
> 	lapic_ipi_vectored(ipi, APIC_IPI_DEST_SELF);
> }
>
> -#ifdef KDB_STOP_NMI
> +#ifdef STOP_NMI
> /*
>  * send NMI IPI to selected CPUs
>  */
> @@ -1252,7 +1285,6 @@
> void
> ipi_nmi_selected(u_int32_t cpus)
> {
> -
> 	int cpu;
> 	register_t icrlo;
>
> @@ -1261,10 +1293,8 @@
>
> 	CTR2(KTR_SMP, "%s: cpus: %x nmi", __func__, cpus);
>
> -
> 	atomic_set_int(&ipi_nmi_pending, cpus);
>
> -
> 	while ((cpu = ffs(cpus)) != 0) {
> 		cpu--;
> 		cpus &= ~(1 << cpu);
> @@ -1276,43 +1306,43 @@
> 		if (!lapic_ipi_wait(BEFORE_SPIN))
> 			panic("ipi_nmi_selected: previous IPI has not cleared");
>
> -		lapic_ipi_raw(icrlo,cpu_apic_ids[cpu]);
> +		lapic_ipi_raw(icrlo, cpu_apic_ids[cpu]);
> 	}
> }
>
> -
> int
> ipi_nmi_handler()
> {
> -	int cpu  = PCPU_GET(cpuid);
> -	void *restartfunc(void);
> +	int cpu = PCPU_GET(cpuid);
> +	int cpumask = PCPU_GET(cpumask);
> +	void (*restartfunc)(void);
>
> -	if(!(atomic_load_acq_int(&ipi_nmi_pending) & (1 << cpu)))
> +	if (!(ipi_nmi_pending & cpumask))
> 		return 1;
>
> -	atomic_clear_int(&ipi_nmi_pending,1 << cpu);
> +	atomic_clear_int(&ipi_nmi_pending, cpumask);
>
> 	savectx(&stoppcbs[cpu]);
>
> 	/* Indicate that we are stopped */
> -	atomic_set_int(&stopped_cpus,1 << cpu);
> +	atomic_set_int(&stopped_cpus, cpumask);
>
> -
> 	/* Wait for restart */
> -	while(!(atomic_load_acq_int(&started_cpus) & (1 << cpu)))
> +	while (!(started_cpus & cpumask))
> 	    ia32_pause();
>
> -	atomic_clear_int(&started_cpus,1 << cpu);
> -	atomic_clear_int(&stopped_cpus,1 << cpu);
> +	atomic_clear_int(&started_cpus, cpumask);
> +	atomic_clear_int(&stopped_cpus, cpumask);
>
> -	restartfunc = (void (*)(void))atomic_readandclear_int(&cpustop_restartfunc);
> +	restartfunc = (void (*)(void))atomic_readandclear_int(
> +		(u_int *)&cpustop_restartfunc);
> 	if (restartfunc != NULL)
> 		restartfunc();
>
> 	return 0;
> }
>
> -#endif /* KDB_STOP_NMI */
> +#endif /* STOP_NMI */
>
> /*
>  * This is called once the rest of the system is up and running and we're
>
> ==== //depot/projects/smpng/sys/i386/i386/trap.c#86 (text+ko) ====
>
> @@ -185,13 +185,13 @@
> 	PCPU_LAZY_INC(cnt.v_trap);
> 	type = frame.tf_trapno;
>
> -#ifdef KDB_STOP_NMI
> -	/* Handler for NMI IPIs used for debugging */
> +#ifdef STOP_NMI
> +	/* Handler for NMI IPIs used for stopping CPUs. */
> 	if (type == T_NMI) {
> 	         if (ipi_nmi_handler() == 0)
> 	                   goto out;
> 	}
> -#endif /* KDB_STOP_NMI */
> +#endif /* STOP_NMI */
>
> #ifdef KDB
> 	if (kdb_active) {
>
> ==== //depot/projects/smpng/sys/i386/include/smp.h#17 (text+ko) ====
>
> @@ -79,9 +79,8 @@
> void	smp_invltlb(void);
> void	smp_masked_invltlb(u_int mask);
>
> -#ifdef KDB_STOP_NMI
> -int ipi_nmi_handler(void);
> -void ipi_nmi_selected(u_int32_t cpus);
> +#ifdef STOP_NMI
> +int	ipi_nmi_handler(void);
> #endif
>
> #endif /* !LOCORE */
>
> ==== //depot/projects/smpng/sys/kern/subr_kdb.c#12 (text+ko) ====
>
> @@ -42,16 +42,11 @@
> #include <machine/kdb.h>
> #include <machine/pcb.h>
>
> -#ifdef KDB_STOP_NMI
> +#ifdef SMP
> +#if defined (__i386__) || defined(__amd64__)
> +#define	HAVE_STOPPEDPCBS
> #include <machine/smp.h>
> #endif
> -
> -/*
> - * KDB_STOP_NMI requires SMP to pick up the right dependencies
> - * (And isn't useful on UP anyway)
> - */
> -#if defined(KDB_STOP_NMI) && !defined(SMP)
> -#error "options KDB_STOP_NMI" requires "options SMP"
> #endif
>
> int kdb_active = 0;
> @@ -91,19 +86,6 @@
> SYSCTL_INT(_debug_kdb, OID_AUTO, stop_cpus, CTLTYPE_INT | CTLFLAG_RW,
>     &kdb_stop_cpus, 0, "");
> TUNABLE_INT("debug.kdb.stop_cpus", &kdb_stop_cpus);
> -
> -#ifdef KDB_STOP_NMI
> -/*
> - * Provide an alternate method of stopping other CPUs. If another CPU has
> - * disabled interrupts the conventional STOP IPI will be blocked. This
> - * NMI-based stop should get through in that case.
> - */
> -static int kdb_stop_cpus_with_nmi = 1;
> -SYSCTL_INT(_debug_kdb, OID_AUTO, stop_cpus_with_nmi, CTLTYPE_INT | CTLFLAG_RW,
> -    &kdb_stop_cpus_with_nmi, 0, "");
> -TUNABLE_INT("debug.kdb.stop_cpus_with_nmi", &kdb_stop_cpus_with_nmi);
> -#endif /* KDB_STOP_NMI */
> -
> #endif
>
> static int
> @@ -335,27 +317,24 @@
>
> struct pcb *
> kdb_thr_ctx(struct thread *thr)
> -#ifdef KDB_STOP_NMI
> {
> -  u_int		cpuid;
> -  struct pcpu *pc;
> +#ifdef HAVE_STOPPEDPCBS
> +	struct pcpu *pc;
> +	u_int cpuid;
> +#endif
>
> -  if (thr == curthread)
> -    return &kdb_pcb;
> +	if (thr == curthread)
> +		return &kdb_pcb;
>
> -  SLIST_FOREACH(pc, &cpuhead, pc_allcpu)  {
> -    cpuid = pc->pc_cpuid;
> -    if (pc->pc_curthread == thr && (atomic_load_acq_int(&stopped_cpus) & (1 << cpuid)))
> -      return &stoppcbs[cpuid];
> -  }
> -
> -  return  thr->td_pcb;
> -}
> -#else
> -{
> -	return ((thr == curthread) ? &kdb_pcb : thr->td_pcb);
> +#ifdef HAVE_STOPPEDPCBS
> +	SLIST_FOREACH(pc, &cpuhead, pc_allcpu)  {
> +		cpuid = pc->pc_cpuid;
> +		if (pc->pc_curthread == thr && (stopped_cpus & (1 << cpuid)))
> +			return &stoppcbs[cpuid];
> +	}
> +#endif
> +	return  thr->td_pcb;
> }
> -#endif /* KDB_STOP_NMI */
>
> struct thread *
> kdb_thr_first(void)
> @@ -452,14 +431,7 @@
>
> #ifdef SMP
> 	if ((did_stop_cpus = kdb_stop_cpus) != 0)
> -	  {
> -#ifdef KDB_STOP_NMI
> -	    if(kdb_stop_cpus_with_nmi)
> -	      stop_cpus_nmi(PCPU_GET(other_cpus));
> -	    else
> -#endif /* KDB_STOP_NMI */
> 		stop_cpus(PCPU_GET(other_cpus));
> -	  }
> #endif
>
> 	kdb_frame = tf;
>
> ==== //depot/projects/smpng/sys/kern/subr_smp.c#42 (text+ko) ====
>
> @@ -35,8 +35,6 @@
> #include <sys/cdefs.h>
> __FBSDID("$FreeBSD: src/sys/kern/subr_smp.c,v 1.196 2005/06/30 03:38:10 peter Exp $");
>
> -#include "opt_kdb.h"
> -
> #include <sys/param.h>
> #include <sys/systm.h>
> #include <sys/kernel.h>
> @@ -258,36 +256,6 @@
> 	return 1;
> }
>
> -#ifdef KDB_STOP_NMI
> -int
> -stop_cpus_nmi(cpumask_t map)
> -{
> -	int i;
> -
> -	if (!smp_started)
> -		return 0;
> -
> -	CTR1(KTR_SMP, "stop_cpus(%x)", map);
> -
> -	/* send the stop IPI to all CPUs in map */
> -	ipi_nmi_selected(map);
> -
> -	i = 0;
> -	while ((atomic_load_acq_int(&stopped_cpus) & map) != map) {
> -		/* spin */
> -		i++;
> -#ifdef DIAGNOSTIC
> -		if (i == 100000) {
> -			printf("timeout stopping cpus\n");
> -			break;
> -		}
> -#endif
> -	}
> -
> -	return 1;
> -}
> -#endif /* KDB_STOP_NMI */
> -
> /*
>  * Called by a CPU to restart stopped CPUs.
>  *
>
> ==== //depot/projects/smpng/sys/notes#61 (text+ko) ====
>
> @@ -67,6 +67,12 @@
>   do this.  That really needs to only be done in spinlock_*() (and maybe some
>   frobbing in intr_execute_handlers()) and needs to happen after the
>   spinlock_*() changes happen.
> +- Change KDB_STOP_NMI to STOP_NMI and make it non-kdb specific
> +  - i386
> +    + compiles
> +  - amd64
> +  - use stoppcbs[] on i386 and amd64 always
> +  - untested
> - KTR change: include __func__ along with __FILE__ and __LINE__ and display
>   it after cpu number by default
> - Cheapen global stats counters via PCPU_LAZY_INC
>
> ==== //depot/projects/smpng/sys/pc98/conf/NOTES#45 (text+ko) ====
>
> @@ -39,7 +39,7 @@
>
> # Debugging options.
> #
> -options		KDB_STOP_NMI		# Stop CPUS using NMI instead of IPI
> +options		STOP_NMI		# Stop CPUS using NMI instead of IPI
>
>
>
>
> ==== //depot/projects/smpng/sys/sys/smp.h#15 (text+ko) ====
>
> @@ -102,9 +102,6 @@
> void	smp_rendezvous_action(void);
> extern	struct mtx smp_ipi_mtx;
>
> -#ifdef KDB_STOP_NMI
> -int	stop_cpus_nmi(cpumask_t);
> -#endif
> #endif /* SMP */
> void	smp_rendezvous(void (*)(void *),
> 		       void (*)(void *),
>


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