Subject: [PATCH] kill useless SMT code in prom_hold_cpus

From: Nathan Lynch <[email-masked]>
Date: Tue, 8 Jul 2008 17:36:31 -0500

I think this code that counts SMT threads and compares against NR_CPUS
is an artifact of pre-powerpc-merge ppc64.  We care about starting
only primary threads in the OF client code.

Signed-off-by: Nathan Lynch <[email-masked]>
---
 arch/powerpc/kernel/prom_init.c |   39 +++------------------------------------
 1 files changed, 3 insertions(+), 36 deletions(-)

diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c
index 1ea8c8d..b1dd86c 100644
--- a/arch/powerpc/kernel/prom_init.c
+++ b/arch/powerpc/kernel/prom_init.c
@@ -205,8 +205,6 @@ static int __initdata mem_reserve_cnt;
 static cell_t __initdata regbuf[1024];

-#define MAX_CPU_THREADS 2
-
 /*
  * Error results ... some OF calls will return "-1" on error, some
  * will return 0, some will return either. To simplify, here are
@@ -1332,10 +1330,6 @@ static void __init prom_hold_cpus(void)
 	unsigned int reg;
 	phandle node;
 	char type[64];
-	int cpuid = 0;
-	unsigned int interrupt_server[MAX_CPU_THREADS];
-	unsigned int cpu_threads, hw_cpu_num;
-	int propsize;
 	struct prom_t *_prom = &RELOC(prom);
 	unsigned long *spinloop
 		= (void *) LOW_ADDR(__secondary_hold_spinloop);
@@ -1379,7 +1373,6 @@ static void __init prom_hold_cpus(void)
 		reg = -1;
 		prom_getprop(node, "reg", &reg, sizeof(reg));
 
-		prom_debug("\ncpuid        = 0x%x\n", cpuid);
 		prom_debug("cpu hw idx   = 0x%x\n", reg);
 
 		/* Init the acknowledge var which will be reset by
@@ -1388,28 +1381,9 @@ static void __init prom_hold_cpus(void)
 		 */
 		*acknowledge = (unsigned long)-1;
 
-		propsize = prom_getprop(node, "ibm,ppc-interrupt-server#s",
-					&interrupt_server,
-					sizeof(interrupt_server));
-		if (propsize < 0) {
-			/* no property.  old hardware has no SMT */
-			cpu_threads = 1;
-			interrupt_server[0] = reg; /* fake it with phys id */
-		} else {
-			/* We have a threaded processor */
-			cpu_threads = propsize / sizeof(u32);
-			if (cpu_threads > MAX_CPU_THREADS) {
-				prom_printf("SMT: too many threads!\n"
-					    "SMT: found %x, max is %x\n",
-					    cpu_threads, MAX_CPU_THREADS);
-				cpu_threads = 1; /* ToDo: panic? */
-			}
-		}
-
-		hw_cpu_num = interrupt_server[0];
-		if (hw_cpu_num != _prom->cpu) {
+		if (reg != _prom->cpu) {
 			/* Primary Thread of non-boot cpu */
-			prom_printf("%x : starting cpu hw idx %x... ", cpuid, reg);
+			prom_printf("starting cpu hw idx %x... ", reg);
 			call_prom("start-cpu", 3, 0, node,
 				  secondary_hold, reg);
 
@@ -1424,17 +1398,10 @@ static void __init prom_hold_cpus(void)
 		}
 #ifdef CONFIG_SMP
 		else
-			prom_printf("%x : boot cpu     %x\n", cpuid, reg);
+			prom_printf("boot cpu hw idx %x\n", reg);
 #endif /* CONFIG_SMP */
-
-		/* Reserve cpu #s for secondary threads.   They start later. */
-		cpuid += cpu_threads;
 	}
 
-	if (cpuid > NR_CPUS)
-		prom_printf("WARNING: maximum CPUs (" __stringify(NR_CPUS)
-			    ") exceeded: ignoring extras\n");
-
 	prom_debug("prom_hold_cpus: end...\n");
 }
 
-- 
1.5.6.2