[patch 0/4] i386, x86_64: fix the irqbalance quirk for E7520/E7320/E7525

[patch 0/4] i386, x86_64: fix the irqbalance quirk for E7520/E7320/E7525

[Siddha, Suresh B]

Mechanism of selecting physical mode in genapic when cpu hotplug is enabled
on x86_64, broke the quirk(quirk_intel_irqbalance()) introduced for working
around the transposing interrupt message errata in E7520/E7320/E7525
(revision ID 0x9 and below. errata #23 in 
http://download.intel.com/design/chipsets/specupdt/30304203.pdf).

This errata requires the mode to be in logical flat, so that interrupts
can be directed to more than one cpu(and thus use hardware IRQ balancing
enabled by BIOS on these platforms).

Following four patches fixes this by moving the quirk to early quirk
and forcing the x86_64 genapic selection to logical flat on these platforms.

Thanks to Shaohua for pointing out the breakage.

[patch 1/4] add write_pci_config_byte() to direct PCI access routines

[Siddha, Suresh B]

Add write_pci_config_byte() to direct PCI access  routines

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
---

diff --git a/arch/i386/pci/early.c b/arch/i386/pci/early.c
index 713d6c8..42df4b6 100644
--- a/arch/i386/pci/early.c
+++ b/arch/i386/pci/early.c
@@ -45,6 +45,13 @@ void write_pci_config(u8 bus, u8 slot, u
 	outl(val, 0xcfc);
 }
 
+void write_pci_config_byte(u8 bus, u8 slot, u8 func, u8 offset, u8 val)
+{
+	PDprintk("%x writing to %x: %x\n", slot, offset, val);
+	outl(0x80000000 | (bus<<16) | (slot<<11) | (func<<8) | offset, 0xcf8);
+	outb(val, 0xcfc);
+}
+
 int early_pci_allowed(void)
 {
 	return (pci_probe & (PCI_PROBE_CONF1|PCI_PROBE_NOEARLY)) ==
diff --git a/include/asm-x86_64/pci-direct.h b/include/asm-x86_64/pci-direct.h
index eba9cb4..6823fa4 100644
--- a/include/asm-x86_64/pci-direct.h
+++ b/include/asm-x86_64/pci-direct.h
@@ -10,6 +10,7 @@ extern u32 read_pci_config(u8 bus, u8 sl
 extern u8 read_pci_config_byte(u8 bus, u8 slot, u8 func, u8 offset);
 extern u16 read_pci_config_16(u8 bus, u8 slot, u8 func, u8 offset);
 extern void write_pci_config(u8 bus, u8 slot, u8 func, u8 offset, u32 val);
+extern void write_pci_config_byte(u8 bus, u8 slot, u8 func, u8 offset, u8 val);
 
 extern int early_pci_allowed(void);
 

Re: [patch 2/4] introduce the mechanism of disabling cpu hotplug control

[Siddha, Suresh B]

Add 'cpu_hotplug_no_control' and when set, the hotplug control file("online")
will not be added under /sys/devices/system/cpu/cpuX/

Next patch doing PCI quirks will use this.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
---

diff --git a/arch/i386/kernel/topology.c b/arch/i386/kernel/topology.c
index 07d6da3..9b766e7 100644
--- a/arch/i386/kernel/topology.c
+++ b/arch/i386/kernel/topology.c
@@ -40,14 +40,22 @@ int arch_register_cpu(int num)
 	 * restrictions and assumptions in kernel. This basically
 	 * doesnt add a control file, one cannot attempt to offline
 	 * BSP.
+	 *
+	 * Also certain PCI quirks require to remove this control file
+	 * for all CPU's.
 	 */
+#ifdef CONFIG_HOTPLUG_CPU
+	if (!num || cpu_hotplug_no_control)
+#else
 	if (!num)
+#endif
 		cpu_devices[num].cpu.no_control = 1;
 
 	return register_cpu(&cpu_devices[num].cpu, num);
 }
 
 #ifdef CONFIG_HOTPLUG_CPU
+int cpu_hotplug_no_control;
 
 void arch_unregister_cpu(int num) {
 	return unregister_cpu(&cpu_devices[num].cpu);
diff --git a/include/asm-i386/cpu.h b/include/asm-i386/cpu.h
index b1bc7b1..3c5da33 100644
--- a/include/asm-i386/cpu.h
+++ b/include/asm-i386/cpu.h
@@ -13,6 +13,7 @@ struct i386_cpu {
 extern int arch_register_cpu(int num);
 #ifdef CONFIG_HOTPLUG_CPU
 extern void arch_unregister_cpu(int);
+extern int cpu_hotplug_no_control;
 #endif
 
 DECLARE_PER_CPU(int, cpu_state);

[patch 3/4] x86_64: add genapic_force

[Siddha, Suresh B]

Add genapic_force. Used by the next Intel quirks patch.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
---

diff --git a/arch/x86_64/kernel/genapic.c b/arch/x86_64/kernel/genapic.c
index 8e78a75..236dc9e 100644
--- a/arch/x86_64/kernel/genapic.c
+++ b/arch/x86_64/kernel/genapic.c
@@ -33,7 +33,7 @@ extern struct genapic apic_flat;
 extern struct genapic apic_physflat;
 
 struct genapic *genapic = &apic_flat;
-
+struct genapic *genapic_force;
 
 /*
  * Check the APIC IDs in bios_cpu_apicid and choose the APIC mode.
@@ -46,6 +46,14 @@ void __init clustered_apic_check(void)
 	u8 cluster_cnt[NUM_APIC_CLUSTERS];
 	int max_apic = 0;
 
+	/* genapic selection can be forced because of certain quirks and
+	 * in future perhaps user can select this through cmdline
+	 */
+	if (genapic_force) {
+		genapic = genapic_force;
+		goto print;
+	}
+
 #if defined(CONFIG_ACPI)
 	/*
 	 * Some x86_64 machines use physical APIC mode regardless of how many
diff --git a/include/asm-x86_64/genapic.h b/include/asm-x86_64/genapic.h
index a0e9a4b..b80f4bb 100644
--- a/include/asm-x86_64/genapic.h
+++ b/include/asm-x86_64/genapic.h
@@ -30,6 +30,6 @@ struct genapic {
 };
 
 
-extern struct genapic *genapic;
+extern struct genapic *genapic, *genapic_force, apic_flat;
 
 #endif

[patch 4/4] fix the irqbalance quirk for E7320/E7520/E7525

[Siddha, Suresh B]

Move the irqbalance quirks for E7320/E7520/E7525(Errata 23 in
http://download.intel.com/design/chipsets/specupdt/30304203.pdf) to early
quirks.

And add a PCI quirk for these platforms to check(which happens very late
during the boot) if the APIC routing is indeed set to default flat mode.

This fixes the breakage(in x86_64) of this quirk due to cpu hotplug which
selects physical mode instead of the logical flat(as needed for this errata
workaround).

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
---

diff --git a/arch/i386/kernel/acpi/earlyquirk.c b/arch/i386/kernel/acpi/earlyquirk.c
index fe799b1..4cdec39 100644
--- a/arch/i386/kernel/acpi/earlyquirk.c
+++ b/arch/i386/kernel/acpi/earlyquirk.c
@@ -10,6 +10,7 @@ #include <linux/acpi.h>
 #include <asm/pci-direct.h>
 #include <asm/acpi.h>
 #include <asm/apic.h>
+#include <asm/irq.h>
 
 #ifdef CONFIG_ACPI
 
@@ -43,6 +44,24 @@ #endif
 	return 0;
 }
 
+static void check_intel(void)
+{
+	u16 vendor, device;
+
+	vendor = read_pci_config_16(0, 0, 0, PCI_VENDOR_ID);
+
+	if (vendor != PCI_VENDOR_ID_INTEL)
+		return;
+
+	device = read_pci_config_16(0, 0, 0, PCI_DEVICE_ID);
+#ifdef CONFIG_SMP
+	if (device == PCI_DEVICE_ID_INTEL_E7320_MCH ||
+	    device == PCI_DEVICE_ID_INTEL_E7520_MCH ||
+	    device == PCI_DEVICE_ID_INTEL_E7525_MCH)
+		quirk_intel_irqbalance();
+#endif
+}
+
 void __init check_acpi_pci(void)
 {
 	int num, slot, func;
@@ -54,6 +73,8 @@ void __init check_acpi_pci(void)
 	if (!early_pci_allowed())
 		return;
 
+	check_intel();
+
 	/* Poor man's PCI discovery */
 	for (num = 0; num < 32; num++) {
 		for (slot = 0; slot < 32; slot++) {
diff --git a/arch/i386/kernel/quirks.c b/arch/i386/kernel/quirks.c
index 9f6ab17..fd8c68c 100644
--- a/arch/i386/kernel/quirks.c
+++ b/arch/i386/kernel/quirks.c
@@ -3,10 +3,28 @@
  */
 #include <linux/pci.h>
 #include <linux/irq.h>
+#include <asm/pci-direct.h>
+#include <asm/genapic.h>
+#include <asm/cpu.h>
 
 #if defined(CONFIG_X86_IO_APIC) && defined(CONFIG_SMP) && defined(CONFIG_PCI)
+static void __devinit verify_quirk_intel_irqbalance(struct pci_dev *dev)
+{
+#ifdef CONFIG_X86_64
+	if (genapic !=  &apic_flat) {
+		printk(KERN_WARNING "APIC mode must be flat on this system\n");
+		BUG();
+	}
+#else
+	if (genapic != &apic_default) {
+		printk(KERN_WARNING
+		       "APIC mode must be default(flat) on this system. Use apic=default\n");
+		BUG();
+	}
+#endif
+}
 
-static void __devinit quirk_intel_irqbalance(struct pci_dev *dev)
+void __init quirk_intel_irqbalance(void)
 {
 	u8 config, rev;
 	u32 word;
@@ -16,18 +34,18 @@ static void __devinit quirk_intel_irqbal
 	 * based platforms.
 	 * Disable SW irqbalance/affinity on those platforms.
 	 */
-	pci_read_config_byte(dev, PCI_CLASS_REVISION, &rev);
+	rev = read_pci_config_byte(0, 0, 0, PCI_CLASS_REVISION);
 	if (rev > 0x9)
 		return;
 
 	printk(KERN_INFO "Intel E7520/7320/7525 detected.");
 
-	/* enable access to config space*/
-	pci_read_config_byte(dev, 0xf4, &config);
-	pci_write_config_byte(dev, 0xf4, config|0x2);
+	/* enable access to config space */
+	config = read_pci_config_byte(0, 0, 0, 0xf4);
+	write_pci_config_byte(0, 0, 0, 0xf4, config|0x2);
 
 	/* read xTPR register */
-	raw_pci_ops->read(0, 0, 0x40, 0x4c, 2, &word);
+	word = read_pci_config_16(0, 0, 0x40, 0x4c);
 
 	if (!(word & (1 << 13))) {
 		printk(KERN_INFO "Disabling irq balancing and affinity\n");
@@ -38,13 +56,24 @@ #endif
 #ifdef CONFIG_PROC_FS
 		no_irq_affinity = 1;
 #endif
+#ifdef CONFIG_HOTPLUG_CPU
+		printk(KERN_INFO "Disabling cpu hotplug control\n");
+		cpu_hotplug_no_control = 1;
+#endif
+#ifdef CONFIG_X86_64
+		/* force the genapic selection to flat mode so that
+		 * interrupts can be redirected to more than one CPU.
+		 */
+		genapic_force = &apic_flat;
+#endif
 	}
 
-	/* put back the original value for config space*/
+	/* put back the original value for config space */
 	if (!(config & 0x2))
-		pci_write_config_byte(dev, 0xf4, config);
+		write_pci_config_byte(0, 0, 0, 0xf4, config);
 }
-DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL,	PCI_DEVICE_ID_INTEL_E7320_MCH,	quirk_intel_irqbalance);
-DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL,	PCI_DEVICE_ID_INTEL_E7525_MCH,	quirk_intel_irqbalance);
-DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL,	PCI_DEVICE_ID_INTEL_E7520_MCH,	quirk_intel_irqbalance);
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL,   PCI_DEVICE_ID_INTEL_E7320_MCH,  verify_quirk_intel_irqbalance);
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL,   PCI_DEVICE_ID_INTEL_E7525_MCH,  verify_quirk_intel_irqbalance);
+DECLARE_PCI_FIXUP_FINAL(PCI_VENDOR_ID_INTEL,   PCI_DEVICE_ID_INTEL_E7520_MCH,  verify_quirk_intel_irqbalance);
+
 #endif
diff --git a/arch/i386/kernel/smpboot.c b/arch/i386/kernel/smpboot.c
index 4bb8b77..79bc607 100644
--- a/arch/i386/kernel/smpboot.c
+++ b/arch/i386/kernel/smpboot.c
@@ -52,6 +52,7 @@ #include <asm/tlbflush.h>
 #include <asm/desc.h>
 #include <asm/arch_hooks.h>
 #include <asm/nmi.h>
+#include <asm/genapic.h>
 
 #include <mach_apic.h>
 #include <mach_wakecpu.h>
@@ -1461,6 +1462,13 @@ #endif
 	cpu_set(cpu, smp_commenced_mask);
 	while (!cpu_isset(cpu, cpu_online_map))
 		cpu_relax();
+
+	if (num_online_cpus() > 8 && genapic == &apic_default) {
+		printk(KERN_WARNING
+		       "Default flat APIC routing can't be used with > 8 cpus\n");
+		BUG();
+	}
+
 	return 0;
 }
 
diff --git a/arch/x86_64/kernel/early-quirks.c b/arch/x86_64/kernel/early-quirks.c
index 2b1245d..a644663 100644
--- a/arch/x86_64/kernel/early-quirks.c
+++ b/arch/x86_64/kernel/early-quirks.c
@@ -68,6 +68,18 @@ static void ati_bugs(void)
 	}
 }
 
+static void intel_bugs(void)
+{
+	u16 device = read_pci_config_16(0, 0, 0, PCI_DEVICE_ID);
+
+#ifdef CONFIG_SMP
+	if (device == PCI_DEVICE_ID_INTEL_E7320_MCH ||
+	    device == PCI_DEVICE_ID_INTEL_E7520_MCH ||
+	    device == PCI_DEVICE_ID_INTEL_E7525_MCH)
+		quirk_intel_irqbalance();
+#endif
+}
+
 struct chipset {
 	u16 vendor;
 	void (*f)(void);
@@ -77,6 +89,7 @@ static struct chipset early_qrk[] = {
 	{ PCI_VENDOR_ID_NVIDIA, nvidia_bugs },
 	{ PCI_VENDOR_ID_VIA, via_bugs },
 	{ PCI_VENDOR_ID_ATI, ati_bugs },
+	{ PCI_VENDOR_ID_INTEL, intel_bugs},
 	{}
 };
 
diff --git a/arch/x86_64/kernel/smpboot.c b/arch/x86_64/kernel/smpboot.c
index 62c2e74..4c161c2 100644
--- a/arch/x86_64/kernel/smpboot.c
+++ b/arch/x86_64/kernel/smpboot.c
@@ -60,6 +60,7 @@ #include <asm/nmi.h>
 #include <asm/irq.h>
 #include <asm/hw_irq.h>
 #include <asm/numa.h>
+#include <asm/genapic.h>
 
 /* Number of siblings per CPU package */
 int smp_num_siblings = 1;
@@ -1167,6 +1168,13 @@ int __cpuinit __cpu_up(unsigned int cpu)
 
 	while (!cpu_isset(cpu, cpu_online_map))
 		cpu_relax();
+
+	if (num_online_cpus() > 8 && genapic == &apic_flat) {
+		printk(KERN_WARNING
+		       "flat APIC routing can't be used with > 8 cpus\n");
+		BUG();
+	}
+
 	err = 0;
 
 	return err;
diff --git a/include/asm-i386/genapic.h b/include/asm-i386/genapic.h
index 8ffbb0f..fd2be59 100644
--- a/include/asm-i386/genapic.h
+++ b/include/asm-i386/genapic.h
@@ -122,6 +122,6 @@ #define APIC_INIT(aname, aprobe) { \
 	APICFUNC(phys_pkg_id) \
 	}
 
-extern struct genapic *genapic;
+extern struct genapic *genapic, apic_default;
 
 #endif
diff --git a/include/asm-i386/irq.h b/include/asm-i386/irq.h
index 331726b..c35dc8e 100644
--- a/include/asm-i386/irq.h
+++ b/include/asm-i386/irq.h
@@ -37,6 +37,8 @@ #ifdef CONFIG_IRQBALANCE
 extern int irqbalance_disable(char *str);
 #endif
 
+extern void quirk_intel_irqbalance(void);
+
 #ifdef CONFIG_HOTPLUG_CPU
 extern void fixup_irqs(cpumask_t map);
 #endif
diff --git a/include/asm-x86_64/proto.h b/include/asm-x86_64/proto.h
index e72cfcd..3b6a4ec 100644
--- a/include/asm-x86_64/proto.h
+++ b/include/asm-x86_64/proto.h
@@ -88,6 +88,7 @@ extern void syscall32_cpu_init(void);
 extern void setup_node_bootmem(int nodeid, unsigned long start, unsigned long end);
 
 extern void early_quirks(void);
+extern void quirk_intel_irqbalance(void);
 extern void check_efer(void);
 
 extern int unhandled_signal(struct task_struct *tsk, int sig);

Re: [patch 2/4] introduce the mechanism of disabling cpu hotplug control

[Andrew Morton]

On Tue, 7 Nov 2006 17:40:25 -0800
"Siddha, Suresh B" <suresh.b.siddha@intel.com> wrote:

> Add 'cpu_hotplug_no_control' and when set, the hotplug control file("online")
> will not be added under /sys/devices/system/cpu/cpuX/
> 
> Next patch doing PCI quirks will use this.
> 

I don't understand what this (ugly) patch has to do with the overall
bugfix.  We're fixing the APCI initialisation - what does that have to do
with presenting cpu-hotplug files in sysfs?


> ---
> 
> diff --git a/arch/i386/kernel/topology.c b/arch/i386/kernel/topology.c
> index 07d6da3..9b766e7 100644
> --- a/arch/i386/kernel/topology.c
> +++ b/arch/i386/kernel/topology.c
> @@ -40,14 +40,22 @@ int arch_register_cpu(int num)
>  	 * restrictions and assumptions in kernel. This basically
>  	 * doesnt add a control file, one cannot attempt to offline
>  	 * BSP.
> +	 *
> +	 * Also certain PCI quirks require to remove this control file
> +	 * for all CPU's.
>  	 */
> +#ifdef CONFIG_HOTPLUG_CPU
> +	if (!num || cpu_hotplug_no_control)
> +#else
>  	if (!num)
> +#endif

This ifdef could be removed 

>  		cpu_devices[num].cpu.no_control = 1;
>  
>  	return register_cpu(&cpu_devices[num].cpu, num);
>  }
>  
>  #ifdef CONFIG_HOTPLUG_CPU
> +int cpu_hotplug_no_control;
>  
>  void arch_unregister_cpu(int num) {
>  	return unregister_cpu(&cpu_devices[num].cpu);
> diff --git a/include/asm-i386/cpu.h b/include/asm-i386/cpu.h
> index b1bc7b1..3c5da33 100644
> --- a/include/asm-i386/cpu.h
> +++ b/include/asm-i386/cpu.h
> @@ -13,6 +13,7 @@ struct i386_cpu {
>  extern int arch_register_cpu(int num);
>  #ifdef CONFIG_HOTPLUG_CPU
>  extern void arch_unregister_cpu(int);
> +extern int cpu_hotplug_no_control;

via:

#else
#define cpu_hotplug_no_control 1

here.


But does this variable _have_ to be a negative like this?  The code would
be simpler if it had the opposite sense and was called, say,
cpu_hotplug_enable_control_file.

Are these patches considered 2.6.19 material?  They look a bit big, ugly
and scary for that.

Re: [patch 2/4] introduce the mechanism of disabling cpu hotplug control

[Siddha, Suresh B]

On Tue, Nov 07, 2006 at 07:54:30PM -0800, Andrew Morton wrote:
> On Tue, 7 Nov 2006 17:40:25 -0800
> "Siddha, Suresh B" <suresh.b.siddha@intel.com> wrote:
> 
> > Add 'cpu_hotplug_no_control' and when set, the hotplug control file("online")
> > will not be added under /sys/devices/system/cpu/cpuX/
> > 
> > Next patch doing PCI quirks will use this.
> > 
> 
> I don't understand what this (ugly) patch has to do with the overall
> bugfix.  We're fixing the APCI initialisation - what does that have to do
> with presenting cpu-hotplug files in sysfs?

This patch is adding a mechanism which will not export the cpu hotplug control
file.  And the quirk will use this from preventing the users doing cpu hotplug.
On these platforms, we need to have atleast 2 cpus online to workaround the
errata.

In future we can use this mechanism to disable cpu hotplug during bootup.

> But does this variable _have_ to be a negative like this?  The code would
> be simpler if it had the opposite sense and was called, say,
> cpu_hotplug_enable_control_file.

I wanted to add something like disable_cpu_hotplug.. but suspend code
seems to be already using.. Will clean this up.

> Are these patches considered 2.6.19 material?  They look a bit big, ugly
> and scary for that.

Though no one reported failures so far, it would be good to get included
in 2.6.19. If it is too late and sounds scary, we can consider in -stable
after spending sometime in -mm..

thanks,
suresh

Re: [patch 2/4] introduce the mechanism of disabling cpu hotplug control

[Andrew Morton]

On Tue, 7 Nov 2006 20:01:34 -0800
"Siddha, Suresh B" <suresh.b.siddha@intel.com> wrote:

> I wanted to add something like disable_cpu_hotplug

My point is, `enable_cpu_hotplug' is nicer

	if (enable_cpu_hotplug)
		...
	if (!enable_cpu_hotplug)
		...

versus

	if (disable_cpu_hotplug)
		...
	if (!disable_cpu_hotplug)
		...			/* My brain hurts */

Re: [patch 2/4] introduce the mechanism of disabling cpu hotplug control

[Siddha, Suresh B]

On Tue, Nov 07, 2006 at 08:35:04PM -0800, Andrew Morton wrote:
> On Tue, 7 Nov 2006 20:01:34 -0800
> "Siddha, Suresh B" <suresh.b.siddha@intel.com> wrote:
> 
> > I wanted to add something like disable_cpu_hotplug
> 
> My point is, `enable_cpu_hotplug' is nicer

Yep. I got it and hence my "will clean this up" assurance :)

This is all coming from the `no_control' member in cpu structure and I will
change that to something like `hotpluggable'. That will make the patch slightly
big but def clean.

thanks,
suresh

[patch] change the 'no_control' field to 'hotpluggable' in the struct cpu

[Siddha, Suresh B]

On Tue, Nov 07, 2006 at 09:23:32PM -0800, Siddha, Suresh B wrote:
> On Tue, Nov 07, 2006 at 08:35:04PM -0800, Andrew Morton wrote:
> > "Siddha, Suresh B" <suresh.b.siddha@intel.com> wrote:
> > 
> > > I wanted to add something like disable_cpu_hotplug
> > 
> > My point is, `enable_cpu_hotplug' is nicer
> 
> Yep. I got it and hence my "will clean this up" assurance :)
> 
> This is all coming from the `no_control' member in cpu structure and I will
> change that to something like `hotpluggable'. That will make the patch slightly
> big but def clean.

Andrew, Appended the cleanup patch which goes on top of your -mm tree.
Please apply. Thanks.
---

Change the 'no_control' field in the cpu struct to a more positive
and better term 'hotpluggable'. And change(/cleanup) the logic accordingly.

Signed-off-by: Suresh Siddha <suresh.b.siddha@intel.com>
---

diff --git a/arch/i386/kernel/topology.c b/arch/i386/kernel/topology.c
index 844c08f..79cf608 100644
--- a/arch/i386/kernel/topology.c
+++ b/arch/i386/kernel/topology.c
@@ -44,8 +44,8 @@ int arch_register_cpu(int num)
 	 * Also certain PCI quirks require not to enable hotplug control
 	 * for all CPU's.
 	 */
-	if (!num || !enable_cpu_hotplug)
-		cpu_devices[num].cpu.no_control = 1;
+	if (num && enable_cpu_hotplug)
+		cpu_devices[num].cpu.hotpluggable = 1;
 
 	return register_cpu(&cpu_devices[num].cpu, num);
 }
diff --git a/arch/ia64/kernel/topology.c b/arch/ia64/kernel/topology.c
index 5629b45..687500d 100644
--- a/arch/ia64/kernel/topology.c
+++ b/arch/ia64/kernel/topology.c
@@ -31,11 +31,11 @@ int arch_register_cpu(int num)
 {
 #if defined (CONFIG_ACPI) && defined (CONFIG_HOTPLUG_CPU)
 	/*
-	 * If CPEI cannot be re-targetted, and this is
-	 * CPEI target, then dont create the control file
+	 * If CPEI can be re-targetted or if this is not
+	 * CPEI target, then it is hotpluggable
 	 */
-	if (!can_cpei_retarget() && is_cpu_cpei_target(num))
-		sysfs_cpus[num].cpu.no_control = 1;
+	if (can_cpei_retarget() || !is_cpu_cpei_target(num))
+		sysfs_cpus[num].cpu.hotpluggable = 1;
 	map_cpu_to_node(num, node_cpuid[num].nid);
 #endif
 
diff --git a/arch/powerpc/kernel/sysfs.c b/arch/powerpc/kernel/sysfs.c
index d45a168..bf65a15 100644
--- a/arch/powerpc/kernel/sysfs.c
+++ b/arch/powerpc/kernel/sysfs.c
@@ -240,7 +240,7 @@ static void unregister_cpu_online(unsign
 	struct cpu *c = &per_cpu(cpu_devices, cpu);
 	struct sys_device *s = &c->sysdev;
 
-	BUG_ON(c->no_control);
+	BUG_ON(!c->hotpluggable);
 
 #ifndef CONFIG_PPC_ISERIES
 	if (cpu_has_feature(CPU_FTR_SMT))
@@ -360,10 +360,10 @@ static int __init topology_init(void)
 		 * CPU.  For instance, the boot cpu might never be valid
 		 * for hotplugging.
 		 */
-		if (!ppc_md.cpu_die)
-			c->no_control = 1;
+		if (ppc_md.cpu_die)
+			c->hotpluggable = 1;
 
-		if (cpu_online(cpu) || (c->no_control == 0)) {
+		if (cpu_online(cpu) || c->hotpluggable) {
 			register_cpu(c, cpu);
 
 			sysdev_create_file(&c->sysdev, &attr_physical_id);
diff --git a/drivers/base/cpu.c b/drivers/base/cpu.c
index 4bef76a..d00c67c 100644
--- a/drivers/base/cpu.c
+++ b/drivers/base/cpu.c
@@ -103,8 +103,8 @@ #endif
 
 /*
  * register_cpu - Setup a driverfs device for a CPU.
- * @cpu - Callers can set the cpu->no_control field to 1, to indicate not to
- *		  generate a control file in sysfs for this CPU.
+ * @cpu - cpu->hotpluggable field set to 1 will generate a control file in
+ *	  sysfs for this CPU.
  * @num - CPU number to use when creating the device.
  *
  * Initialize and register the CPU device.
@@ -118,7 +118,7 @@ int __devinit register_cpu(struct cpu *c
 
 	error = sysdev_register(&cpu->sysdev);
 
-	if (!error && !cpu->no_control)
+	if (!error && cpu->hotpluggable)
 		register_cpu_control(cpu);
 	if (!error)
 		cpu_sys_devices[num] = &cpu->sysdev;
diff --git a/include/linux/cpu.h b/include/linux/cpu.h
index 3fef7d6..a1fd791 100644
--- a/include/linux/cpu.h
+++ b/include/linux/cpu.h
@@ -27,7 +27,7 @@ #include <asm/semaphore.h>
 
 struct cpu {
 	int node_id;		/* The node which contains the CPU */
-	int no_control;		/* Should the sysfs control file be created? */
+	int hotpluggable;	/* creates sysfs control file if hotpluggable */
 	struct sys_device sysdev;
 };
 

Re: [patch 0/4] i386, x86_64: fix the irqbalance quirk for E7520/E7320/E7525

[Andrew Morton]

On Tue, 7 Nov 2006 17:33:06 -0800
"Siddha, Suresh B" <suresh.b.siddha@intel.com> wrote:

> Mechanism of selecting physical mode in genapic when cpu hotplug is enabled
> on x86_64, broke the quirk(quirk_intel_irqbalance()) introduced for working
> around the transposing interrupt message errata in E7520/E7320/E7525
> (revision ID 0x9 and below. errata #23 in 
> http://download.intel.com/design/chipsets/specupdt/30304203.pdf).
> 
> This errata requires the mode to be in logical flat, so that interrupts
> can be directed to more than one cpu(and thus use hardware IRQ balancing
> enabled by BIOS on these platforms).
> 
> Following four patches fixes this by moving the quirk to early quirk
> and forcing the x86_64 genapic selection to logical flat on these platforms.
> 
> Thanks to Shaohua for pointing out the breakage.

It blew up with the first config I tried
(http://userweb.kernel.org/~akpm/config-vmm.txt):

arch/i386/kernel/built-in.o: In function `verify_quirk_intel_irqbalance':
arch/i386/kernel/quirks.c:19: undefined reference to `genapic'
arch/i386/kernel/quirks.c:19: undefined reference to `apic_default'
arch/i386/kernel/built-in.o: In function `__cpu_up':
arch/i386/kernel/smpboot.c:1487: undefined reference to `genapic'
arch/i386/kernel/smpboot.c:1487: undefined reference to `apic_default'

The dependencies in the code which you're touching here are really really
complex and fragile.  One needs to review the change very carefully and
test it exhaustively.

Re: [patch 0/4] i386, x86_64: fix the irqbalance quirk for E7520/E7320/E7525

[Siddha, Suresh B]

On Tue, Nov 07, 2006 at 08:07:02PM -0800, Andrew Morton wrote:
> arch/i386/kernel/built-in.o: In function `verify_quirk_intel_irqbalance':
> arch/i386/kernel/quirks.c:19: undefined reference to `genapic'
> arch/i386/kernel/quirks.c:19: undefined reference to `apic_default'
> arch/i386/kernel/built-in.o: In function `__cpu_up':
> arch/i386/kernel/smpboot.c:1487: undefined reference to `genapic'
> arch/i386/kernel/smpboot.c:1487: undefined reference to `apic_default'
> 
> The dependencies in the code which you're touching here are really really
> complex and fragile.  One needs to review the change very carefully and
> test it exhaustively.

oops. I did compile and boot with 6 x86/x86_64 configs.. Seems something
is broken in my git test tree. Let me fix and getback to you.

thanks,
suresh