From: "Fenghua Yu" <fenghua.yu@intel.com>
To: "Ingo Molnar" <mingo@elte.hu>,
"Thomas Gleixner" <tglx@linutronix.de>,
"H Peter Anvin" <hpa@zytor.com>,
"Linus Torvalds" <torvalds@linux-foundation.org>,
"Andrew Morton" <akpm@linux-foundation.org>,
"Asit K Mallick" <asit.k.mallick@intel.com>,
"Tony Luck" <tony.luck@intel.com>,
"Arjan Dan De Ven" <arjan@linux.intel.com>,
"Suresh B Siddha" <suresh.b.siddha@intel.com>,
"Len Brown" <len.brown@intel.com>,
"Srivatssa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>,
"Randy Dunlap" <rdunlap@xenotime.net>,
"Chen Gong" <gong.chen@linux.intel.com>,
"linux-kernel" <linux-kernel@vger.kernel.org>,
"linux-pm" <linux-pm@vger.kernel.org>, "x86" <x86@kernel.org>
Cc: "Fenghua Yu" <fenghua.yu@intel.com>
Subject: [PATCH v6 03/12] x86/topology.c: Support functions for CPU0 online/offline
Date: Thu, 10 May 2012 09:16:45 -0700 [thread overview]
Message-ID: <1336666614-21090-4-git-send-email-fenghua.yu@intel.com> (raw)
In-Reply-To: <1336666614-21090-1-git-send-email-fenghua.yu@intel.com>
From: Fenghua Yu <fenghua.yu@intel.com>
If CONFIG_BOOTPARAM_HOTPLUG_CPU is turned on, CPU0 hotplug feature is enabled
by default.
If CONFIG_BOOTPARAM_HOTPLUG_CPU is not turned on, CPU0 hotplug feature is not
enabled by default. The kernel parameter cpu0_hotplug can enable CPU0 hotplug
feature at boot.
Signed-off-by: Fenghua Yu <fenghua.yu@intel.com>
---
arch/x86/kernel/topology.c | 27 ++++++++++++++++++++-------
1 files changed, 20 insertions(+), 7 deletions(-)
diff --git a/arch/x86/kernel/topology.c b/arch/x86/kernel/topology.c
index 76ee977..8cec15c 100644
--- a/arch/x86/kernel/topology.c
+++ b/arch/x86/kernel/topology.c
@@ -35,18 +35,31 @@
static DEFINE_PER_CPU(struct x86_cpu, cpu_devices);
#ifdef CONFIG_HOTPLUG_CPU
+
+#ifdef CONFIG_BOOTPARAM_HOTPLUG_CPU0
+static int __initdata cpu0_hotpluggable = 1;
+#else
+static int __initdata cpu0_hotpluggable;
+static int __init enable_cpu0_hotplug(char *str)
+{
+ cpu0_hotpluggable = 1;
+ return 1;
+}
+
+__setup("cpu0_hotplug", enable_cpu0_hotplug);
+#endif
+
int __ref arch_register_cpu(int num)
{
/*
- * CPU0 cannot be offlined due to several
- * restrictions and assumptions in kernel. This basically
- * doesn't add a control file, one cannot attempt to offline
- * BSP.
+ * Two known BSP/CPU0 dependencies: Resume from suspend/hibernate
+ * depends on BSP. PIC interrupts depend on BSP.
*
- * Also certain PCI quirks require not to enable hotplug control
- * for all CPU's.
+ * If the BSP depencies are under control, one can tell kernel to
+ * enable BSP hotplug. This basically adds a control file and
+ * one can attempt to offline BSP.
*/
- if (num)
+ if (num || cpu0_hotpluggable)
per_cpu(cpu_devices, num).cpu.hotpluggable = 1;
return register_cpu(&per_cpu(cpu_devices, num).cpu, num);
--
1.6.0.3
next prev parent reply other threads:[~2012-05-10 16:33 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-05-10 16:16 [PATCH v6 0/12] x86: Arbitrary CPU hot(un)plug support Fenghua Yu
2012-05-10 16:16 ` [PATCH v6 01/12] Documentations/cpu-hotplug.tx, kernel-parameters.txt: Add x86 CPU0 online/offline feature Fenghua Yu
2012-05-10 16:16 ` [PATCH v6 02/12] x86/Kconfig: Add config switch for CPU0 hotplug Fenghua Yu
2012-05-10 16:16 ` Fenghua Yu [this message]
2012-05-10 16:16 ` [PATCH v6 04/12] x86/smpboot.c: Don't offline CPU0 if any irq can not be migrated out of it and remove CPU0 check in smp_callin() Fenghua Yu
2012-05-11 12:05 ` Thomas Gleixner
2012-05-11 18:42 ` Tony Luck
2012-05-14 12:17 ` Ingo Molnar
2012-05-14 16:40 ` Luck, Tony
2012-05-14 20:03 ` Yu, Fenghua
2012-05-17 22:47 ` Suresh Siddha
2012-05-18 1:47 ` Yu, Fenghua
2012-05-18 3:34 ` H. Peter Anvin
2012-05-17 22:52 ` H. Peter Anvin
2012-05-18 6:46 ` Ingo Molnar
2012-05-10 16:16 ` [PATCH v6 05/12] x86/power/cpu.c: Don't hibernate/suspend if CPU0 is offline Fenghua Yu
2012-05-10 16:16 ` [PATCH v6 06/12] x86/head_64.S: Define start_cpu0 Fenghua Yu
2012-05-10 16:16 ` [PATCH v6 07/12] x86/head_32.S: " Fenghua Yu
2012-05-10 17:31 ` H. Peter Anvin
2012-05-10 20:48 ` Yu, Fenghua
2012-05-10 23:53 ` H. Peter Anvin
2012-05-10 16:16 ` [PATCH v6 08/12] x86/smpboot.c: Wake up CPU0 via NMI instead of INITs Fenghua Yu
2012-05-10 16:16 ` [PATCH v6 09/12] x86/common.c: Init CPU0 data during CPU0 online Fenghua Yu
2012-05-10 16:16 ` [PATCH v6 10/12] x86/mtrr/main.c: Ask the first online CPU to save mtrr Fenghua Yu
2012-05-10 16:16 ` [PATCH v6 11/12] x86/i387.c: Thread xstate is initialized only on CPU0 once Fenghua Yu
2012-05-10 16:16 ` [PATCH v6 12/12] x86/topology.c: debug CPU0 hotplug Fenghua Yu
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=1336666614-21090-4-git-send-email-fenghua.yu@intel.com \
--to=fenghua.yu@intel.com \
--cc=akpm@linux-foundation.org \
--cc=arjan@linux.intel.com \
--cc=asit.k.mallick@intel.com \
--cc=gong.chen@linux.intel.com \
--cc=hpa@zytor.com \
--cc=len.brown@intel.com \
--cc=linux-kernel@vger.kernel.org \
--cc=linux-pm@vger.kernel.org \
--cc=mingo@elte.hu \
--cc=rdunlap@xenotime.net \
--cc=srivatsa.bhat@linux.vnet.ibm.com \
--cc=suresh.b.siddha@intel.com \
--cc=tglx@linutronix.de \
--cc=tony.luck@intel.com \
--cc=torvalds@linux-foundation.org \
--cc=x86@kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).