Bug 153177

Summary:	With HT off in bios, /proc/cpuinfo shows2 processors, each with 2 siblings
Product:	Red Hat Enterprise Linux 4	Reporter:	Christopher P Johnson <christopher.p.johnson>
Component:	kernel	Assignee:	Jim Paradis <jparadis>
Status:	CLOSED DUPLICATE	QA Contact:	Brian Brock <bbrock>
Severity:	medium	Docs Contact:
Priority:	medium
Version:	4.0	CC:	jbaron, linux-bugs, peterm, riel, shillman
Target Milestone:	---
Target Release:	---
Hardware:	i386
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2005-12-07 18:33:51 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description Christopher P Johnson 2005-04-02 01:04:12 UTC

Description of problem:

See http://bugme.osdl.org/show_bug.cgi?id=4359

Steps to reproduce:

On an HP DL-360 or Sun Fire V60x (dual xeon systems)
  1. disable HT in the bios
  2. boot any smp kernel after 2.6.5 (didn't try UP kernel)
  3. /proc/cpuinfo shows 2 processors (phys ID 0 and 3) with 2 siblings

Expected behavior:
 /proc/cpuinfo should show 2 processors with 1 sibling each.

Additional info:

The x86_64 kernel already provides the following code to workaround
this issue. Please add it to the i386 kernel.

--- linux-2.6.6-1.435.2.3/arch/i386/kernel/smpboot.c.org	2005-03-19
06:56:51.123416256 -0800
+++ linux-2.6.6-1.435.2.3/arch/i386/kernel/smpboot.c	2005-03-19
06:59:01.884537544 -0800
@@ -1110,8 +1110,12 @@ static void __init smp_boot_cpus(unsigne
 			cpu_set(cpu, cpu_sibling_map[cpu]);
 		}
 
-		if (siblings != smp_num_siblings)
+		if (siblings != smp_num_siblings) {
 			printk(KERN_WARNING "WARNING: %d siblings found for CPU%d, should be %d\n",
siblings, cpu, smp_num_siblings);
+			printk(KERN_WARNING "WARNING: BIOS reporting wrong sibling count. Resetting
it to %d\n", siblings);
+			smp_num_siblings = siblings;
+		}
+
 	}
 
 	if (nmi_watchdog == NMI_LOCAL_APIC)

Comment 1 Suzanne Hillman 2005-04-04 19:45:49 UTC

Please attach the patch to this bug using the "Create a New Attachment" link.

Comment 2 Jim Paradis 2005-12-07 18:33:51 UTC


*** This bug has been marked as a duplicate of 169472 ***