Re: [PATCH 1/2] acpi: Fix the mapping handle in case of declaring processors using the Device operator

From: Dou Liyang
Date: Thu Feb 16 2017 - 20:48:59 EST

At 02/16/2017 09:06 PM, Hanjun Guo wrote:
On 2017/2/16 18:38, Dou Liyang wrote:
In ACPI spec, we can declare processors using both Processor and
Device operator. But now, we just handle the mapping of processors
which are declared by Processor operator.

It misses the processors declared by Device operator.

The patch adds this case of the Device operator.

Signed-off-by: Dou Liyang <douly.fnst@xxxxxxxxxxxxxx>
drivers/acpi/processor_core.c | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/acpi/processor_core.c
index 611a558..1aab5b0 100644
--- a/drivers/acpi/processor_core.c
+++ b/drivers/acpi/processor_core.c
@@ -344,8 +344,10 @@ void __init acpi_set_processor_mapping(void)
/* Set persistent cpu <-> node mapping for all processors. */
- ACPI_UINT32_MAX, set_processor_node_mapping,
+ ACPI_UINT32_MAX, set_processor_node_mapping,

no need to update the code above.

Here is some format problem I fixed, but it looks like I didn't do
anything. I will modify it in next version.

+ acpi_get_devices(ACPI_PROCESSOR_DEVICE_HID,

It makes sense to me to add support for Processor devices of setting
persistent cpu <-> node mapping, but I just wondering if there is no
Processor device or Processor Operator for a processor entry(such as
local apic, the spec didn't say it's a mandatory) in MADT,

It is in DSDT. Declare processprs like:

Processor (ProcessorName, ProcessorID, PBlockAddress, PblockLength) { ObjectList }


Device (DeviceName) { ObjectList }

how do we
set the mappings?

Step 1. we generate the logical CPU IDs by the Local APIC/x2APIC ID in
MADT. So, we have the mapping of CPU ID <-> Local Apic ID. We also can
get the mapping of Processor ID/UID <-> Local Apic ID directly in MADT.

195 [0ECh 0236 1] Subtable Type : 00 [Processor Local APIC]
196 [0EDh 0237 1] Length : 08
197 [0EEh 0238 1] *Processor ID : 40*
198 [0EFh 0239 1] *Local Apic ID : 40*
199 [0F0h 0240 4] Flags (decoded below) : 00000001
200 Processor Enabled : 1

So, at last, we get the mapping of

*Processor ID/UID <-> Local Apic ID <-> CPU ID*

Step 2. we can get *processorID/_UID <-> Node ID(_PXM)* in DSDT.

So, we get the maaping of *Node ID <-> CPU ID* according to

*Node ID(_PXM) <-> Processor ID/UID <-> Local Apic ID <-> CPU ID*

BTW, multi places in the ACPI driver are using the same pattern here
to scan all the processors, maybe we can add a function then call it
to reduce some lines of code?

Yes, I think so.


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