linux-kernel - [PATCH 7/10] x86_64: use core id bits for apicid_to

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Message-id: <200707231309.22829.yinghai.lu@sun.com>
Date:	Mon, 23 Jul 2007 13:09:22 -0700
From:	Yinghai Lu <Yinghai.Lu@....COM>
To:	Andi Kleen <ak@...e.de>, Andrew Morton <akpm@...ux-foundation.org>
Cc:	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: [PATCH 7/10] x86_64: use core id bits for apicid_to_node initialization

[PATCH 7/10] x86_64: use core id bits for apicid_to_node initialization

We shoud use core id bits instead of max cores, in case later with AMD
downcores Quad core Opteron.

Signed-off-by: Yinghai Lu <yhlu.kernel@...il.com>

diff --git a/arch/x86_64/mm/k8topology.c b/arch/x86_64/mm/k8topology.c
index a96006f..7cbd58a 100644
--- a/arch/x86_64/mm/k8topology.c
+++ b/arch/x86_64/mm/k8topology.c
@@ -44,12 +44,14 @@ int __init k8_scan_nodes(unsigned long start, unsigned long end)
 { 
 	unsigned long prevbase;
 	struct bootnode nodes[8];
-	int nodeid, i, j, nb;
+	int nodeid, i, nb;
 	unsigned char nodeids[8];
 	int found = 0;
 	u32 reg;
 	unsigned numnodes;
-	unsigned num_cores;
+	unsigned cores;
+	unsigned bits;
+	int j;
 
 	if (!early_pci_allowed())
 		return -1;
@@ -60,9 +62,6 @@ int __init k8_scan_nodes(unsigned long start, unsigned long end)
 
 	printk(KERN_INFO "Scanning NUMA topology in Northbridge %d\n", nb); 
 
-	num_cores = (cpuid_ecx(0x80000008) & 0xff) + 1;
-	printk(KERN_INFO "CPU has %d num_cores\n", num_cores);
-
 	reg = read_pci_config(0, nb, 0, 0x60); 
 	numnodes = ((reg >> 4) & 0xF) + 1;
 	if (numnodes <= 1)
@@ -168,11 +167,15 @@ int __init k8_scan_nodes(unsigned long start, unsigned long end)
 	} 
 	printk(KERN_INFO "Using node hash shift of %d\n", memnode_shift); 
 
+	/* use the coreid bits from early_identify_cpu */
+	bits = boot_cpu_data.x86_coreid_bits;
+	cores = (1<<bits);
+
 	for (i = 0; i < 8; i++) {
 		if (nodes[i].start != nodes[i].end) { 
 			nodeid = nodeids[i];
-			for (j = 0; j < num_cores; j++)
-				apicid_to_node[(nodeid * num_cores) + j] = i;
+			for (j = 0; j < cores; j++)
+				apicid_to_node[(nodeid << bits) + j] = i;
 			setup_node_bootmem(i, nodes[i].start, nodes[i].end); 
 		} 
 	}
-
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