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Date: Mon, 16 Nov 2009 14:51:41 -0800
From: Mike Travis <travis@....com>
To: "H. Peter Anvin" <hpa@...or.com>
CC: Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
Andrew Morton <akpm@...ux-foundation.org>,
Heiko Carstens <heiko.carstens@...ibm.com>,
Roland Dreier <rdreier@...co.com>,
Randy Dunlap <rdunlap@...otime.net>, Tejun Heo <tj@...nel.org>,
Andi Kleen <andi@...stfloor.org>,
Greg Kroah-Hartman <gregkh@...e.de>,
Yinghai Lu <yhlu.kernel@...il.com>,
David Rientjes <rientjes@...gle.com>,
Steven Rostedt <rostedt@...dmis.org>,
Rusty Russell <rusty@...tcorp.com.au>,
Hidetoshi Seto <seto.hidetoshi@...fujitsu.com>,
Jack Steiner <steiner@....com>,
Frederic Weisbecker <fweisbec@...il.com>, x86@...nel.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/6] INIT: Limit the number of per cpu calibration bootup
messages
H. Peter Anvin wrote:
> On 11/16/2009 01:45 PM, Mike Travis wrote:
>>
>> Ingo Molnar wrote:
>>> * Mike Travis <travis@....com> wrote:
>>>
>>>> --- linux.orig/init/calibrate.c
>>>> +++ linux/init/calibrate.c
>>>> @@ -123,23 +123,26 @@
>>>> {
>>>> unsigned long ticks, loopbit;
>>>> int lps_precision = LPS_PREC;
>>>> + bool boot_cpu = (smp_processor_id() == 0);
>>> this code is shared by other architectures too - are you sure
>>> smp_processor_id()==0 is a proper 'I am the boot CPU' assumption
>>> everywhere?
>>>
>>> Ingo
>> This was where having the boot_cpu_id would have been handy.
>>
>> I could add something like:
>>
>> --- linux.orig/init/main.c
>> +++ linux/init/main.c
>> @@ -539,13 +539,15 @@
>> * Activate the first processor.
>> */
>>
>> +int boot_cpu_id __read_mostly;
> ^^^^^^^^^^^^^^^
>> +
>> static void __init boot_cpu_init(void)
>> {
>> - int cpu = smp_processor_id();
>> + int boot_cpu_id = smp_processor_id();
> ^^^^^^^^^^^^^^^
>> /* Mark the boot cpu "present", "online" etc for SMP and UP case */
>
> Doesn't really work, does it?
>
> I also still think that wrapping it in an inline would be good.
>
> -hpa
Yes, a bit quick on the reply button. But the proposal was clear enough?
I've just looked at this, and there are many, many references in arch-specific
code to a scalar "boot_cpu_id". Maybe a better approach would be to add an
inline named something else? get_boot_cpu_id() perhaps? Or an inline
function "is_boot_cpu()" ... ?
There's also some confusion on whether the boot_cpu_id is the APIC id (ia64)
or the cpu_index (x86) or some other number (others). (cpu_index 0 by
definition will always be the boot cpu.)
Here's an initial stab (by no means complete) at adding boot_cpu_id(). As
you can see the reach is quite extensive.
INIT: Identify processor id of boot cpu
Provide an architecture-independent means of identifying
the boot cpu's processor id.
Signed-of-by: Mike Travis <travis@....com>
---
arch/alpha/kernel/smp.c | 2 +-
arch/sparc/kernel/smp_32.c | 1 -
arch/x86/include/asm/cpu.h | 2 --
arch/x86/kernel/apic/io_apic.c | 10 +++++-----
arch/x86/kernel/cpu/amd.c | 2 +-
arch/x86/kernel/cpu/common.c | 4 ++--
arch/x86/kernel/cpu/intel.c | 2 +-
arch/x86/kernel/setup.c | 2 --
arch/x86/kernel/setup_percpu.c | 4 ++--
include/linux/smp.h | 13 +++++++++++++
init/main.c | 12 +++++++-----
11 files changed, 32 insertions(+), 22 deletions(-)
--- linux.orig/arch/alpha/kernel/smp.c
+++ linux/arch/alpha/kernel/smp.c
@@ -633,7 +633,7 @@
cpumask_t to_whom = cpu_possible_map;
cpu_clear(smp_processor_id(), to_whom);
#ifdef DEBUG_IPI_MSG
- if (hard_smp_processor_id() != boot_cpu_id)
+ if (hard_smp_processor_id() != boot_cpu_id())
printk(KERN_WARNING "smp_send_stop: Not on boot cpu.\n");
#endif
send_ipi_message(&to_whom, IPI_CPU_STOP);
--- linux.orig/arch/sparc/kernel/smp_32.c
+++ linux/arch/sparc/kernel/smp_32.c
@@ -36,7 +36,6 @@
#include "irq.h"
volatile unsigned long cpu_callin_map[NR_CPUS] __cpuinitdata = {0,};
-unsigned char boot_cpu_id = 0;
unsigned char boot_cpu_id4 = 0; /* boot_cpu_id << 2 */
cpumask_t smp_commenced_mask = CPU_MASK_NONE;
--- linux.orig/arch/x86/include/asm/cpu.h
+++ linux/arch/x86/include/asm/cpu.h
@@ -32,6 +32,4 @@
DECLARE_PER_CPU(int, cpu_state);
-extern unsigned int boot_cpu_id;
-
#endif /* _ASM_X86_CPU_H */
--- linux.orig/arch/x86/kernel/apic/io_apic.c
+++ linux/arch/x86/kernel/apic/io_apic.c
@@ -197,7 +197,7 @@
cfg = irq_cfgx;
count = ARRAY_SIZE(irq_cfgx);
- node= cpu_to_node(boot_cpu_id);
+ node= cpu_to_node(boot_cpu_id());
for (i = 0; i < count; i++) {
desc = irq_to_desc(i);
@@ -1496,7 +1496,7 @@
int notcon = 0;
struct irq_desc *desc;
struct irq_cfg *cfg;
- int node = cpu_to_node(boot_cpu_id);
+ int node = cpu_to_node(boot_cpu_id());
apic_printk(APIC_VERBOSE, KERN_DEBUG "init IO_APIC IRQs\n");
@@ -2828,7 +2828,7 @@
{
struct irq_desc *desc = irq_to_desc(0);
struct irq_cfg *cfg = desc->chip_data;
- int node = cpu_to_node(boot_cpu_id);
+ int node = cpu_to_node(boot_cpu_id());
int apic1, pin1, apic2, pin2;
unsigned long flags;
int no_pin1 = 0;
@@ -3184,7 +3184,7 @@
int create_irq(void)
{
- int node = cpu_to_node(boot_cpu_id);
+ int node = cpu_to_node(boot_cpu_id());
unsigned int irq_want;
int irq;
@@ -3861,7 +3861,7 @@
if (dev)
node = dev_to_node(dev);
else
- node = cpu_to_node(boot_cpu_id);
+ node = cpu_to_node(boot_cpu_id());
desc = irq_to_desc_alloc_node(irq, node);
if (!desc) {
--- linux.orig/arch/x86/kernel/cpu/amd.c
+++ linux/arch/x86/kernel/cpu/amd.c
@@ -148,7 +148,7 @@
{
#ifdef CONFIG_SMP
/* calling is from identify_secondary_cpu() ? */
- if (c->cpu_index == boot_cpu_id)
+ if (raw_smp_processor_id() == boot_cpu_id())
return;
/*
--- linux.orig/arch/x86/kernel/cpu/common.c
+++ linux/arch/x86/kernel/cpu/common.c
@@ -649,7 +649,7 @@
this_cpu->c_early_init(c);
#ifdef CONFIG_SMP
- c->cpu_index = boot_cpu_id;
+ c->cpu_index = boot_cpu_id();
#endif
filter_cpuid_features(c, false);
}
@@ -1251,7 +1251,7 @@
/*
* Boot processor to setup the FP and extended state context info.
*/
- if (smp_processor_id() == boot_cpu_id)
+ if (smp_processor_id() == boot_cpu_id())
init_thread_xstate();
xsave_init();
--- linux.orig/arch/x86/kernel/cpu/intel.c
+++ linux/arch/x86/kernel/cpu/intel.c
@@ -149,7 +149,7 @@
{
#ifdef CONFIG_SMP
/* calling is from identify_secondary_cpu() ? */
- if (c->cpu_index == boot_cpu_id)
+ if (raw_smp_processor_id() == boot_cpu_id())
return;
/*
--- linux.orig/arch/x86/kernel/setup.c
+++ linux/arch/x86/kernel/setup.c
@@ -120,8 +120,6 @@
RESERVE_BRK(dmi_alloc, 65536);
-unsigned int boot_cpu_id __read_mostly;
-
static __initdata unsigned long _brk_start = (unsigned long)__brk_base;
unsigned long _brk_end = (unsigned long)__brk_base;
--- linux.orig/arch/x86/kernel/setup_percpu.c
+++ linux/arch/x86/kernel/setup_percpu.c
@@ -243,7 +243,7 @@
* Up to this point, the boot CPU has been using .data.init
* area. Reload any changed state for the boot CPU.
*/
- if (cpu == boot_cpu_id)
+ if (cpu == boot_cpu_id())
switch_to_new_gdt(cpu);
}
@@ -261,7 +261,7 @@
* make sure boot cpu node_number is right, when boot cpu is on the
* node that doesn't have mem installed
*/
- per_cpu(node_number, boot_cpu_id) = cpu_to_node(boot_cpu_id);
+ per_cpu(node_number, boot_cpu_id()) = cpu_to_node(boot_cpu_id());
#endif
/* Setup node to cpumask map */
--- linux.orig/include/linux/smp.h
+++ linux/include/linux/smp.h
@@ -109,6 +109,17 @@
*/
void smp_prepare_boot_cpu(void);
+/*
+ * Identify processor ID of boot cpu
+ */
+extern int _boot_cpu_id;
+
+static inline int boot_cpu_id(void)
+{
+ return _boot_cpu_id;
+}
+
+
extern unsigned int setup_max_cpus;
#else /* !SMP */
@@ -119,6 +130,8 @@
* These macros fold the SMP functionality into a single CPU system
*/
#define raw_smp_processor_id() 0
+#define boot_cpu_id() 0
+
static inline int up_smp_call_function(void (*func)(void *), void *info)
{
return 0;
--- linux.orig/init/main.c
+++ linux/init/main.c
@@ -538,14 +538,16 @@
/*
* Activate the first processor.
*/
+int _boot_cpu_id __read_mostly;
+EXPORT_SYMBOL(_boot_cpu_id);
-static void __init boot_cpu_init(void)
+void __init __weak boot_cpu_init(void)
{
- int cpu = smp_processor_id();
/* Mark the boot cpu "present", "online" etc for SMP and UP case */
- set_cpu_online(cpu, true);
- set_cpu_present(cpu, true);
- set_cpu_possible(cpu, true);
+ _boot_cpu_id = raw_smp_processor_id();
+ set_cpu_online(_boot_cpu_id, true);
+ set_cpu_present(_boot_cpu_id, true);
+ set_cpu_possible(_boot_cpu_id, true);
}
void __init __weak smp_setup_processor_id(void)
--
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