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Date: Mon, 12 Dec 2011 10:38:31 +0800
From: Lin Ming <ming.m.lin@...el.com>
To: wallak@...e.fr
Cc: Bjorn Helgaas <bhelgaas@...gle.com>, linux-kernel@...r.kernel.org,
linux-acpi <linux-acpi@...r.kernel.org>, lenb <lenb@...nel.org>
Subject: Re: ACPI "_PDC" - acpi_processor_set_pdc()- execution regression -
Linux-3.x
On Mon, 2011-12-12 at 10:26 +0800, Lin Ming wrote:
> ---------- Forwarded message ----------
> From: <wallak@...e.fr>
> Date: Thu, Dec 8, 2011 at 6:38 AM
> Subject: ACPI "_PDC" - acpi_processor_set_pdc()- execution regression
> - Linux-3.x
> To: linux-kernel@...r.kernel.org
>
>
> We have a regression on the ACPI stack of the last linux kernel line 3.x (3.1.4,
> 3.2-rc4...). The ACPI "_PDC" chunk is not executed on some computers (e.g. Dell
> X300; the function acpi_processor_set_pdc() is not called). This issue yield to
> an uninitialized state of some ACPI variables.
>
> A patch is available below. This patch come back to the previous linux behavior,
> and works fine.
>
> Best Regards,
> Wallak.
>
> --- linux-3.1.4-mdf/drivers/acpi/processor_core.c.orig 2011-12-07
> 23:12:57.000000000 +0100
> +++ linux-3.1.4-mdf/drivers/acpi/processor_core.c 2011-12-07
> 23:13:39.000000000 +0100
> @@ -223,8 +223,8 @@
> type = (acpi_type == ACPI_TYPE_DEVICE) ? 1 : 0;
> cpuid = acpi_get_cpuid(handle, type, acpi_id);
>
> - if (cpuid == -1)
> - return false;
> + if ((cpuid == -1) && (num_possible_cpus() > 1))
Hi Wallak,
BIOS may define multiple CPU handles even for UP
processor(see below).
processor_physically_present(acpi_handle handle) will be called for each
CPU handles.
We should only return valid value for CPU0 on UP processor.
With your patch, processor_physically_present will return true for all
CPU handles(CPU0, CPU1, CPU2, CPU3). This is not we want.
I think below is the correct fix.
Could you help to test it?
Thanks.
>From 5c6de7311ced7a1febf85fdcc08b6116bcfe8138 Mon Sep 17 00:00:00 2001
From: Lin Ming <ming.m.lin@...el.com>
Date: Mon, 12 Dec 2011 10:04:53 +0800
Subject: [PATCH] ACPI: processor: fix acpi_get_cpuid for UP processor
For UP processor, it is likely that no _MAT method or MADT table defined.
So currently acpi_get_cpuid(...) always return -1 for UP processor.
This is wrong. It should return valid value for CPU0.
In the other hand, BIOS may define multiple CPU handles even for UP
processor, for example
Scope (_PR)
{
Processor (CPU0, 0x00, 0x00000410, 0x06) {}
Processor (CPU1, 0x01, 0x00000410, 0x06) {}
Processor (CPU2, 0x02, 0x00000410, 0x06) {}
Processor (CPU3, 0x03, 0x00000410, 0x06) {}
}
We should only return valid value for CPU0's acpi handle.
And return invalid value for others.
http://marc.info/?t=132329819900003&r=1&w=2
Reported-by: wallak@...e.fr
Signed-off-by: Lin Ming <ming.m.lin@...el.com>
---
drivers/acpi/processor_core.c | 26 ++++++++++++++++++++++++--
1 files changed, 24 insertions(+), 2 deletions(-)
diff --git a/drivers/acpi/processor_core.c b/drivers/acpi/processor_core.c
index 3a0428e..3372900 100644
--- a/drivers/acpi/processor_core.c
+++ b/drivers/acpi/processor_core.c
@@ -173,8 +173,30 @@ int acpi_get_cpuid(acpi_handle handle, int type, u32 acpi_id)
apic_id = map_mat_entry(handle, type, acpi_id);
if (apic_id == -1)
apic_id = map_madt_entry(type, acpi_id);
- if (apic_id == -1)
- return apic_id;
+ if (apic_id == -1) {
+ /*
+ * On UP processor, there is no _MAT or MADT table.
+ * So above apic_id is always set to -1.
+ *
+ * BIOS may define multiple CPU handles even for UP processor.
+ * For example,
+ *
+ * Scope (_PR)
+ * {
+ * Processor (CPU0, 0x00, 0x00000410, 0x06) {}
+ * Processor (CPU1, 0x01, 0x00000410, 0x06) {}
+ * Processor (CPU2, 0x02, 0x00000410, 0x06) {}
+ * Processor (CPU3, 0x03, 0x00000410, 0x06) {}
+ * }
+ *
+ * Ignores apic_id and always return 0 for CPU0's handle.
+ * Return -1 for other CPU's handle.
+ */
+ if (acpi_id == 0)
+ return acpi_id;
+ else
+ return apic_id;
+ }
#ifdef CONFIG_SMP
for_each_possible_cpu(i) {
--
1.7.2.5
> + return false;
>
> return true;
> }
--
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