* Make SMP x86-64 kernels boot on more UP systems.
@ 2006-02-24 1:41 Dave Jones
2006-02-24 1:45 ` Andi Kleen
0 siblings, 1 reply; 3+ messages in thread
From: Dave Jones @ 2006-02-24 1:41 UTC (permalink / raw)
To: ak; +Cc: Linux Kernel
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));
^ permalink raw reply [flat|nested] 3+ messages in thread* Re: Make SMP x86-64 kernels boot on more UP systems.
2006-02-24 1:41 Make SMP x86-64 kernels boot on more UP systems Dave Jones
@ 2006-02-24 1:45 ` Andi Kleen
2006-02-24 2:11 ` Dave Jones
0 siblings, 1 reply; 3+ messages in thread
From: Andi Kleen @ 2006-02-24 1:45 UTC (permalink / raw)
To: Dave Jones; +Cc: Linux Kernel
On Friday 24 February 2006 02:41, Dave Jones wrote:
> Should someone boot an SMP kernel on UP hardware on some systems,
> strange things happen, such as..
Boot logs?
> 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");
> + }
It's the wrong place to handle this. Better would be in mpparse.c
-Andi
^ permalink raw reply [flat|nested] 3+ messages in thread
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2006-02-24 1:41 Make SMP x86-64 kernels boot on more UP systems Dave Jones
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