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From: Dave Jones <davej@redhat.com>
To: ak@suse.de
Cc: Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Make SMP x86-64 kernels boot on more UP systems.
Date: Thu, 23 Feb 2006 20:41:12 -0500	[thread overview]
Message-ID: <20060224014112.GA16089@redhat.com> (raw)

Should someone boot an SMP kernel on UP hardware on some systems,
strange things happen, such as..

SMP: Allowing 0 CPUs.

We blow up shortly afterwards.

Signed-off-by: Dave Jones <davej@redhat.com>

--- linux-2.6.15.noarch/arch/x86_64/kernel/smpboot.c~	2006-02-20 21:59:56.000000000 -0500
+++ linux-2.6.15.noarch/arch/x86_64/kernel/smpboot.c	2006-02-20 22:01:57.000000000 -0500
@@ -975,6 +975,11 @@ __init void prefill_possible_map(void)
 	if (possible > NR_CPUS) 
 		possible = NR_CPUS;
 
+	if (possible == 0) {	/* Could be SMP kernel on UP hw with broken BIOS */
+		possible = 1;
+		printk (KERN_DEBUG "BIOS never enumerated boot CPU, fixing.\n");
+	}
+
 	printk(KERN_INFO "SMP: Allowing %d CPUs, %d hotplug CPUs\n",
 		possible,
 	        max_t(int, possible - num_processors, 0));

             reply	other threads:[~2006-02-24  1:41 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2006-02-24  1:41 Dave Jones [this message]
2006-02-24  1:45 ` Make SMP x86-64 kernels boot on more UP systems Andi Kleen
2006-02-24  2:11   ` Dave Jones

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