linux-kernel - [PATCH 7/8] x86: use num_processors for possible cpus

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Date:	Fri, 12 Feb 2010 18:49:49 -0800
From:	Yinghai Lu <yinghai@...nel.org>
To:	Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
	"H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Suresh Siddha <suresh.b.siddha@...el.com>,
	Eric Biederman <ebiederm@...ssion.com>,
	linux-kernel@...r.kernel.org, Yinghai Lu <yinghai@...nel.org>
Subject: [PATCH 7/8] x86: use num_processors for possible cpus

some systems that have disable cpus entries because same
  BIOS will support 2 sockets and 4 sockets and more at
  same time, BIOS just leave some disable entries, but
  those system do not support cpu hotplug. we don't need
  treat disabled_cpus as hotplug cpus.
so we can make nr_cpu_ids smaller and save more space
  (pcpu data allocations), and could make some systems run
  with logical flat instead of physical flat apic mode

-v2: change to black list instead
-v3: just remove that, and the one use possible_cpus= directly.

Signed-off-by: Yinghai Lu <yinghai@...nel.org>
---
 arch/x86/kernel/smpboot.c |    3 +--
 1 files changed, 1 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index da99eef..51ec4b6 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -1194,7 +1194,6 @@ early_param("possible_cpus", _setup_possible_cpus);
  * - Ashok Raj
  *
  * Three ways to find out the number of additional hotplug CPUs:
- * - If the BIOS specified disabled CPUs in ACPI/mptables use that.
  * - The user can overwrite it with possible_cpus=NUM
  * - Otherwise don't reserve additional CPUs.
  * We do this because additional CPUs waste a lot of memory.
@@ -1209,7 +1208,7 @@ __init void prefill_possible_map(void)
 		num_processors = 1;
 
 	if (setup_possible_cpus == -1)
-		possible = num_processors + disabled_cpus;
+		possible = num_processors;
 	else
 		possible = setup_possible_cpus;
 
-- 
1.6.4.2

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