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-rw-r--r--arch/mips/Kconfig12
-rw-r--r--arch/mips/kernel/Makefile2
-rw-r--r--arch/mips/kernel/genex.S1
-rw-r--r--arch/mips/kernel/smp_mt.c366
-rw-r--r--arch/mips/kernel/traps.c14
-rw-r--r--arch/mips/kernel/vpe.c15
-rw-r--r--arch/mips/mips-boards/generic/time.c51
7 files changed, 448 insertions, 13 deletions
diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
index 5af30d385ac..8746e1b1621 100644
--- a/arch/mips/Kconfig
+++ b/arch/mips/Kconfig
@@ -1344,6 +1344,14 @@ config CPU_HAS_PREFETCH
config MIPS_MT
bool "Enable MIPS MT"
+choice
+ prompt "MIPS MT options"
+ depends on MIPS_MT
+
+config MIPS_MT_SMP
+ bool "Use 1 TC on each available VPE for SMP"
+ select SMP
+
config MIPS_VPE_LOADER
bool "VPE loader support."
depends on MIPS_MT
@@ -1351,6 +1359,8 @@ config MIPS_VPE_LOADER
Includes a loader for loading an elf relocatable object
onto another VPE and running it.
+endchoice
+
config MIPS_VPE_LOADER_TOM
bool "Load VPE program into memory hidden from linux"
depends on MIPS_VPE_LOADER
@@ -1496,7 +1506,7 @@ source "mm/Kconfig"
config SMP
bool "Multi-Processing support"
- depends on CPU_RM9000 || (SIBYTE_SB1250 && !SIBYTE_STANDALONE) || SGI_IP27
+ depends on CPU_RM9000 || (SIBYTE_SB1250 && !SIBYTE_STANDALONE) || SGI_IP27 || MIPS_MT_SMP
---help---
This enables support for systems with more than one CPU. If you have
a system with only one CPU, like most personal computers, say N. If
diff --git a/arch/mips/kernel/Makefile b/arch/mips/kernel/Makefile
index 0f527063a8a..4c09e1acafd 100644
--- a/arch/mips/kernel/Makefile
+++ b/arch/mips/kernel/Makefile
@@ -34,6 +34,8 @@ obj-$(CONFIG_CPU_R6000) += r6000_fpu.o r4k_switch.o
obj-$(CONFIG_SMP) += smp.o
+obj-$(CONFIG_MIPS_MT_SMP) += smp_mt.o
+
obj-$(CONFIG_MIPS_VPE_LOADER) += vpe.o
obj-$(CONFIG_MIPS_VPE_APSP_API) += rtlx.o
diff --git a/arch/mips/kernel/genex.S b/arch/mips/kernel/genex.S
index fd904d1e419..aa18a8b7b38 100644
--- a/arch/mips/kernel/genex.S
+++ b/arch/mips/kernel/genex.S
@@ -323,6 +323,7 @@ NESTED(nmi_handler, PT_SIZE, sp)
BUILD_HANDLER mdmx mdmx sti silent /* #22 */
BUILD_HANDLER watch watch sti verbose /* #23 */
BUILD_HANDLER mcheck mcheck cli verbose /* #24 */
+ BUILD_HANDLER mt mt sti verbose /* #25 */
BUILD_HANDLER dsp dsp sti silent /* #26 */
BUILD_HANDLER reserved reserved sti verbose /* others */
diff --git a/arch/mips/kernel/smp_mt.c b/arch/mips/kernel/smp_mt.c
new file mode 100644
index 00000000000..d429544ba4b
--- /dev/null
+++ b/arch/mips/kernel/smp_mt.c
@@ -0,0 +1,366 @@
+/*
+ * Copyright (C) 2004, 2005 MIPS Technologies, Inc. All rights reserved.
+ *
+ * Elizabeth Clarke (beth@mips.com)
+ *
+ * This program is free software; you can distribute it and/or modify it
+ * under the terms of the GNU General Public License (Version 2) as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
+ * for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program; if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place - Suite 330, Boston MA 02111-1307, USA.
+ *
+ */
+#include <linux/kernel.h>
+#include <linux/sched.h>
+#include <linux/cpumask.h>
+#include <linux/interrupt.h>
+#include <linux/compiler.h>
+
+#include <asm/atomic.h>
+#include <asm/cpu.h>
+#include <asm/processor.h>
+#include <asm/system.h>
+#include <asm/hardirq.h>
+#include <asm/mmu_context.h>
+#include <asm/smp.h>
+#include <asm/time.h>
+#include <asm/mipsregs.h>
+#include <asm/mipsmtregs.h>
+#include <asm/cacheflush.h>
+#include <asm/mips-boards/maltaint.h>
+
+#define MIPS_CPU_IPI_RESCHED_IRQ 0
+#define MIPS_CPU_IPI_CALL_IRQ 1
+
+static int cpu_ipi_resched_irq, cpu_ipi_call_irq;
+
+#if 0
+static void dump_mtregisters(int vpe, int tc)
+{
+ printk("vpe %d tc %d\n", vpe, tc);
+
+ settc(tc);
+
+ printk(" c0 status 0x%lx\n", read_vpe_c0_status());
+ printk(" vpecontrol 0x%lx\n", read_vpe_c0_vpecontrol());
+ printk(" vpeconf0 0x%lx\n", read_vpe_c0_vpeconf0());
+ printk(" tcstatus 0x%lx\n", read_tc_c0_tcstatus());
+ printk(" tcrestart 0x%lx\n", read_tc_c0_tcrestart());
+ printk(" tcbind 0x%lx\n", read_tc_c0_tcbind());
+ printk(" tchalt 0x%lx\n", read_tc_c0_tchalt());
+}
+#endif
+
+void __init sanitize_tlb_entries(void)
+{
+ int i, tlbsiz;
+ unsigned long mvpconf0, ncpu;
+
+ if (!cpu_has_mipsmt)
+ return;
+
+ set_c0_mvpcontrol(MVPCONTROL_VPC);
+
+ /* Disable TLB sharing */
+ clear_c0_mvpcontrol(MVPCONTROL_STLB);
+
+ mvpconf0 = read_c0_mvpconf0();
+
+ printk(KERN_INFO "MVPConf0 0x%lx TLBS %lx PTLBE %ld\n", mvpconf0,
+ (mvpconf0 & MVPCONF0_TLBS) >> MVPCONF0_TLBS_SHIFT,
+ (mvpconf0 & MVPCONF0_PTLBE) >> MVPCONF0_PTLBE_SHIFT);
+
+ tlbsiz = (mvpconf0 & MVPCONF0_PTLBE) >> MVPCONF0_PTLBE_SHIFT;
+ ncpu = ((mvpconf0 & MVPCONF0_PVPE) >> MVPCONF0_PVPE_SHIFT) + 1;
+
+ printk(" tlbsiz %d ncpu %ld\n", tlbsiz, ncpu);
+
+ if (tlbsiz > 0) {
+ /* share them out across the vpe's */
+ tlbsiz /= ncpu;
+
+ printk(KERN_INFO "setting Config1.MMU_size to %d\n", tlbsiz);
+
+ for (i = 0; i < ncpu; i++) {
+ settc(i);
+
+ if (i == 0)
+ write_c0_config1((read_c0_config1() & ~(0x3f << 25)) | (tlbsiz << 25));
+ else
+ write_vpe_c0_config1((read_vpe_c0_config1() & ~(0x3f << 25)) |
+ (tlbsiz << 25));
+ }
+ }
+
+ clear_c0_mvpcontrol(MVPCONTROL_VPC);
+}
+
+#if 0
+/*
+ * Use c0_MVPConf0 to find out how many CPUs are available, setting up
+ * phys_cpu_present_map and the logical/physical mappings.
+ */
+void __init prom_build_cpu_map(void)
+{
+ int i, num, ncpus;
+
+ cpus_clear(phys_cpu_present_map);
+
+ /* assume we boot on cpu 0.... */
+ cpu_set(0, phys_cpu_present_map);
+ __cpu_number_map[0] = 0;
+ __cpu_logical_map[0] = 0;
+
+ if (cpu_has_mipsmt) {
+ ncpus = ((read_c0_mvpconf0() & (MVPCONF0_PVPE)) >> MVPCONF0_PVPE_SHIFT) + 1;
+ for (i=1, num=0; i< NR_CPUS && i<ncpus; i++) {
+ cpu_set(i, phys_cpu_present_map);
+ __cpu_number_map[i] = ++num;
+ __cpu_logical_map[num] = i;
+ }
+
+ printk(KERN_INFO "%i available secondary CPU(s)\n", num);
+ }
+}
+#endif
+
+static void ipi_resched_dispatch (struct pt_regs *regs)
+{
+ do_IRQ(MIPS_CPU_IPI_RESCHED_IRQ, regs);
+}
+
+static void ipi_call_dispatch (struct pt_regs *regs)
+{
+ do_IRQ(MIPS_CPU_IPI_CALL_IRQ, regs);
+}
+
+irqreturn_t ipi_resched_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+{
+ return IRQ_HANDLED;
+}
+
+irqreturn_t ipi_call_interrupt(int irq, void *dev_id, struct pt_regs *regs)
+{
+ smp_call_function_interrupt();
+
+ return IRQ_HANDLED;
+}
+
+static struct irqaction irq_resched = {
+ .handler = ipi_resched_interrupt,
+ .flags = SA_INTERRUPT,
+ .name = "IPI_resched"
+};
+
+static struct irqaction irq_call = {
+ .handler = ipi_call_interrupt,
+ .flags = SA_INTERRUPT,
+ .name = "IPI_call"
+};
+
+/*
+ * Common setup before any secondaries are started
+ * Make sure all CPU's are in a sensible state before we boot any of the
+ * secondarys
+ */
+void prom_prepare_cpus(unsigned int max_cpus)
+{
+ unsigned long val;
+ int i, num;
+
+ if (!cpu_has_mipsmt)
+ return;
+
+ /* disable MT so we can configure */
+ dvpe();
+ dmt();
+
+ /* Put MVPE's into 'configuration state' */
+ set_c0_mvpcontrol(MVPCONTROL_VPC);
+
+ val = read_c0_mvpconf0();
+
+ /* we'll always have more TC's than VPE's, so loop setting everything
+ to a sensible state */
+ for (i = 0, num = 0; i <= ((val & MVPCONF0_PTC) >> MVPCONF0_PTC_SHIFT); i++) {
+ settc(i);
+
+ /* VPE's */
+ if (i <= ((val & MVPCONF0_PVPE) >> MVPCONF0_PVPE_SHIFT)) {
+
+ /* deactivate all but vpe0 */
+ if (i != 0) {
+ unsigned long tmp = read_vpe_c0_vpeconf0();
+
+ tmp &= ~VPECONF0_VPA;
+
+ /* master VPE */
+ tmp |= VPECONF0_MVP;
+ write_vpe_c0_vpeconf0(tmp);
+
+ /* Record this as available CPU */
+ if (i < max_cpus) {
+ cpu_set(i, phys_cpu_present_map);
+ __cpu_number_map[i] = ++num;
+ __cpu_logical_map[num] = i;
+ }
+ }
+
+ /* disable multi-threading with TC's */
+ write_vpe_c0_vpecontrol(read_vpe_c0_vpecontrol() & ~VPECONTROL_TE);
+
+ if (i != 0) {
+ write_vpe_c0_status((read_c0_status() & ~(ST0_IM | ST0_IE | ST0_KSU)) | ST0_CU0);
+ write_vpe_c0_cause(read_vpe_c0_cause() & ~CAUSEF_IP);
+
+ /* set config to be the same as vpe0, particularly kseg0 coherency alg */
+ write_vpe_c0_config( read_c0_config());
+ }
+
+ }
+
+ /* TC's */
+
+ if (i != 0) {
+ unsigned long tmp;
+
+ /* bind a TC to each VPE, May as well put all excess TC's
+ on the last VPE */
+ if ( i >= (((val & MVPCONF0_PVPE) >> MVPCONF0_PVPE_SHIFT)+1) )
+ write_tc_c0_tcbind(read_tc_c0_tcbind() | ((val & MVPCONF0_PVPE) >> MVPCONF0_PVPE_SHIFT) );
+ else {
+ write_tc_c0_tcbind( read_tc_c0_tcbind() | i);
+
+ /* and set XTC */
+ write_vpe_c0_vpeconf0( read_vpe_c0_vpeconf0() | (i << VPECONF0_XTC_SHIFT));
+ }
+
+ tmp = read_tc_c0_tcstatus();
+
+ /* mark not allocated and not dynamically allocatable */
+ tmp &= ~(TCSTATUS_A | TCSTATUS_DA);
+ tmp |= TCSTATUS_IXMT; /* interrupt exempt */
+ write_tc_c0_tcstatus(tmp);
+
+ write_tc_c0_tchalt(TCHALT_H);
+ }
+ }
+
+ /* Release config state */
+ clear_c0_mvpcontrol(MVPCONTROL_VPC);
+
+ /* We'll wait until starting the secondaries before starting MVPE */
+
+ printk(KERN_INFO "Detected %i available secondary CPU(s)\n", num);
+
+ /* set up ipi interrupts */
+ if (cpu_has_vint) {
+ set_vi_handler (MIPS_CPU_IPI_RESCHED_IRQ, ipi_resched_dispatch);
+ set_vi_handler (MIPS_CPU_IPI_CALL_IRQ, ipi_call_dispatch);
+ }
+
+ cpu_ipi_resched_irq = MIPSCPU_INT_BASE + MIPS_CPU_IPI_RESCHED_IRQ;
+ cpu_ipi_call_irq = MIPSCPU_INT_BASE + MIPS_CPU_IPI_CALL_IRQ;
+
+ setup_irq(cpu_ipi_resched_irq, &irq_resched);
+ setup_irq(cpu_ipi_call_irq, &irq_call);
+
+ /* need to mark IPI's as IRQ_PER_CPU */
+ irq_desc[cpu_ipi_resched_irq].status |= IRQ_PER_CPU;
+ irq_desc[cpu_ipi_call_irq].status |= IRQ_PER_CPU;
+}
+
+/*
+ * Setup the PC, SP, and GP of a secondary processor and start it
+ * running!
+ * smp_bootstrap is the place to resume from
+ * __KSTK_TOS(idle) is apparently the stack pointer
+ * (unsigned long)idle->thread_info the gp
+ * assumes a 1:1 mapping of TC => VPE
+ */
+void prom_boot_secondary(int cpu, struct task_struct *idle)
+{
+ dvpe();
+ set_c0_mvpcontrol(MVPCONTROL_VPC);
+
+ settc(cpu);
+
+ /* restart */
+ write_tc_c0_tcrestart((unsigned long)&smp_bootstrap);
+
+ /* enable the tc this vpe/cpu will be running */
+ write_tc_c0_tcstatus((read_tc_c0_tcstatus() & ~TCSTATUS_IXMT) | TCSTATUS_A);
+
+ write_tc_c0_tchalt(0);
+
+ /* enable the VPE */
+ write_vpe_c0_vpeconf0(read_vpe_c0_vpeconf0() | VPECONF0_VPA);
+
+ /* stack pointer */
+ write_tc_gpr_sp( __KSTK_TOS(idle));
+
+ /* global pointer */
+ write_tc_gpr_gp((unsigned long)idle->thread_info);
+
+ flush_icache_range((unsigned long)idle->thread_info,
+ (unsigned long)idle->thread_info +
+ sizeof(struct thread_info));
+
+ /* finally out of configuration and into chaos */
+ clear_c0_mvpcontrol(MVPCONTROL_VPC);
+
+ evpe(EVPE_ENABLE);
+}
+
+void prom_init_secondary(void)
+{
+ write_c0_status((read_c0_status() & ~ST0_IM ) |
+ (STATUSF_IP0 | STATUSF_IP1 | STATUSF_IP7));
+}
+
+void prom_smp_finish(void)
+{
+ write_c0_compare(read_c0_count() + (8* mips_hpt_frequency/HZ));
+
+ local_irq_enable();
+}
+
+void prom_cpus_done(void)
+{
+}
+
+void core_send_ipi(int cpu, unsigned int action)
+{
+ int i;
+ unsigned long flags;
+ int vpflags;
+
+ local_irq_save (flags);
+
+ vpflags = dvpe(); /* cant access the other CPU's registers whilst MVPE enabled */
+
+ switch (action) {
+ case SMP_CALL_FUNCTION:
+ i = C_SW1;
+ break;
+
+ case SMP_RESCHEDULE_YOURSELF:
+ default:
+ i = C_SW0;
+ break;
+ }
+
+ /* 1:1 mapping of vpe and tc... */
+ settc(cpu);
+ write_vpe_c0_cause(read_vpe_c0_cause() | i);
+ evpe(vpflags);
+
+ local_irq_restore(flags);
+}
diff --git a/arch/mips/kernel/traps.c b/arch/mips/kernel/traps.c
index 876aff71cd2..e38f24b2b3d 100644
--- a/arch/mips/kernel/traps.c
+++ b/arch/mips/kernel/traps.c
@@ -28,6 +28,8 @@
#include <asm/cpu.h>
#include <asm/dsp.h>
#include <asm/fpu.h>
+#include <asm/mipsregs.h>
+#include <asm/mipsmtregs.h>
#include <asm/module.h>
#include <asm/pgtable.h>
#include <asm/ptrace.h>
@@ -56,6 +58,7 @@ extern asmlinkage void handle_tr(void);
extern asmlinkage void handle_fpe(void);
extern asmlinkage void handle_mdmx(void);
extern asmlinkage void handle_watch(void);
+extern asmlinkage void handle_mt(void);
extern asmlinkage void handle_dsp(void);
extern asmlinkage void handle_mcheck(void);
extern asmlinkage void handle_reserved(void);
@@ -797,6 +800,14 @@ asmlinkage void do_mcheck(struct pt_regs *regs)
(regs->cp0_status & ST0_TS) ? "" : "not ");
}
+asmlinkage void do_mt(struct pt_regs *regs)
+{
+ die_if_kernel("MIPS MT Thread exception in kernel", regs);
+
+ force_sig(SIGILL, current);
+}
+
+
asmlinkage void do_dsp(struct pt_regs *regs)
{
if (cpu_has_dsp)
@@ -1338,6 +1349,9 @@ void __init trap_init(void)
if (cpu_has_mcheck)
set_except_vector(24, handle_mcheck);
+ if (cpu_has_mipsmt)
+ set_except_vector(25, handle_mt);
+
if (cpu_has_dsp)
set_except_vector(26, handle_dsp);
diff --git a/arch/mips/kernel/vpe.c b/arch/mips/kernel/vpe.c
index 6bf42ba08f0..97fefcc9dbe 100644
--- a/arch/mips/kernel/vpe.c
+++ b/arch/mips/kernel/vpe.c
@@ -32,7 +32,7 @@
* mknod /dev/vpe0 c 63 0
* mknod /dev/vpe1 c 63 1
*/
-
+#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/fs.h>
@@ -49,6 +49,7 @@
#include <linux/poll.h>
#include <linux/bootmem.h>
#include <asm/mipsregs.h>
+#include <asm/mipsmtregs.h>
#include <asm/cacheflush.h>
#include <asm/atomic.h>
#include <asm/cpu.h>
@@ -697,7 +698,7 @@ int vpe_run(vpe_t * v)
dvpe();
/* Put MVPE's into 'configuration state' */
- write_c0_mvpcontrol(read_c0_mvpcontrol() | MVPCONTROL_VPC);
+ set_c0_mvpcontrol(MVPCONTROL_VPC);
if (!list_empty(&v->tc)) {
if ((t = list_entry(v->tc.next, struct tc, tc)) == NULL) {
@@ -760,7 +761,7 @@ int vpe_run(vpe_t * v)
write_vpe_c0_cause(0);
/* take system out of configuration state */
- write_c0_mvpcontrol(read_c0_mvpcontrol() & ~MVPCONTROL_VPC);
+ clear_c0_mvpcontrol(MVPCONTROL_VPC);
/* clear interrupts enabled IE, ERL, EXL, and KSU from c0 status */
write_vpe_c0_status(read_vpe_c0_status() & ~(ST0_ERL | ST0_KSU | ST0_IE | ST0_EXL));
@@ -1134,7 +1135,7 @@ int vpe_free(vpe_handle vpe)
evpe_flags = dvpe();
/* Put MVPE's into 'configuration state' */
- write_c0_mvpcontrol(read_c0_mvpcontrol() | MVPCONTROL_VPC);
+ set_c0_mvpcontrol(MVPCONTROL_VPC);
settc(t->index);
write_vpe_c0_vpeconf0(read_vpe_c0_vpeconf0() & ~VPECONF0_VPA);
@@ -1145,7 +1146,7 @@ int vpe_free(vpe_handle vpe)
v->state = VPE_STATE_UNUSED;
- write_c0_mvpcontrol(read_c0_mvpcontrol() & ~MVPCONTROL_VPC);
+ clear_c0_mvpcontrol(MVPCONTROL_VPC);
evpe(evpe_flags);
return 0;
@@ -1191,7 +1192,7 @@ static int __init vpe_module_init(void)
dvpe();
/* Put MVPE's into 'configuration state' */
- write_c0_mvpcontrol(read_c0_mvpcontrol() | MVPCONTROL_VPC);
+ set_c0_mvpcontrol(MVPCONTROL_VPC);
/* dump_mtregs(); */
@@ -1270,7 +1271,7 @@ static int __init vpe_module_init(void)
}
/* release config state */
- write_c0_mvpcontrol(read_c0_mvpcontrol() & ~MVPCONTROL_VPC);
+ clear_c0_mvpcontrol(MVPCONTROL_VPC);
return 0;
}
diff --git a/arch/mips/mips-boards/generic/time.c b/arch/mips/mips-boards/generic/time.c
index 3a6f1428b2c..72a12d931cb 100644
--- a/arch/mips/mips-boards/generic/time.c
+++ b/arch/mips/mips-boards/generic/time.c
@@ -61,6 +61,15 @@ static unsigned int display_count = 0;
static unsigned int timer_tick_count=0;
static int mips_cpu_timer_irq;
+static inline void scroll_display_message(void)
+{
+ if ((timer_tick_count++ % HZ) == 0) {
+ mips_display_message(&display_string[display_count++]);
+ if (display_count == MAX_DISPLAY_COUNT)
+ display_count = 0;
+ }
+}
+
static void mips_timer_dispatch (struct pt_regs *regs)
{
do_IRQ (mips_cpu_timer_irq, regs);
@@ -68,17 +77,42 @@ static void mips_timer_dispatch (struct pt_regs *regs)
irqreturn_t mips_timer_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
+#ifdef CONFIG_SMP
+ int cpu = smp_processor_id();
+
+ if (cpu == 0) {
+ /*
+ * CPU 0 handles the global timer interrupt job and process accounting
+ * resets count/compare registers to trigger next timer int.
+ */
+ (void) timer_interrupt(irq, dev_id, regs);
+ scroll_display_message();
+ }
+ else {
+ /* Everyone else needs to reset the timer int here as
+ ll_local_timer_interrupt doesn't */
+ /*
+ * FIXME: need to cope with counter underflow.
+ * More support needs to be added to kernel/time for
+ * counter/timer interrupts on multiple CPU's
+ */
+ write_c0_compare (read_c0_count() + (mips_hpt_frequency/HZ));
+ /*
+ * other CPUs should do profiling and process accounting
+ */
+ local_timer_interrupt (irq, dev_id, regs);
+ }
+
+ return IRQ_HANDLED;
+#else
irqreturn_t r;
r = timer_interrupt(irq, dev_id, regs);
- if ((timer_tick_count++ % HZ) == 0) {
- mips_display_message(&display_string[display_count++]);
- if (display_count == MAX_DISPLAY_COUNT)
- display_count = 0;
- }
+ scroll_display_message();
return r;
+#endif
}
/*
@@ -176,6 +210,13 @@ void __init mips_timer_setup(struct irqaction *irq)
irq->handler = mips_timer_interrupt; /* we use our own handler */
setup_irq(mips_cpu_timer_irq, irq);
+#ifdef CONFIG_SMP
+ /* irq_desc(riptor) is a global resource, when the interrupt overlaps
+ on seperate cpu's the first one tries to handle the second interrupt.
+ The effect is that the int remains disabled on the second cpu.
+ Mark the interrupt with IRQ_PER_CPU to avoid any confusion */
+ irq_desc[mips_cpu_timer_irq].status |= IRQ_PER_CPU;
+#endif
/* to generate the first timer interrupt */
write_c0_compare (read_c0_count() + mips_hpt_frequency/HZ);