From: Nathan Lynch <ntl@pobox.com>
Date: Sun, 27 Jul 2008 05:24:50 +0000 (+1000)
Subject: powerpc: kill useless SMT code in prom_hold_cpus
X-Git-Tag: v2.6.27-rc1~27^2~17
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7d2f6075f992d33c7be829c3638b8cb72b782b19;p=linux-2.6

powerpc: kill useless SMT code in prom_hold_cpus

This piece of code is broken for >2 threads, and possibly in some
other subtle ways (such as comparing a value obtained from an
"ibm,ppc-interrupt-server#s" property to a value obtained from a
"reg" property) and doesn't seem to have any useful purpose in the
first place other than a dubious warning in case NR_CPUS is too
small, which probably isn't the right place to do so.

Signed-off-by: Nathan Lynch <ntl@pobox.com>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
---

diff --git a/arch/powerpc/kernel/prom_init.c b/arch/powerpc/kernel/prom_init.c
index c4ab2195b9..b72849ac7d 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
@@ -1339,10 +1337,6 @@ 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);
@@ -1386,7 +1380,6 @@ 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
@@ -1395,28 +1388,9 @@ 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);
 
@@ -1431,17 +1405,10 @@ 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");
 }