linux-kernel - Re: [RFC PATCH v2 15/35] ACPI: processor: Add support for processors described as container packages

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Message-ID: <ZUTbiO2/SSFcTPAV@shell.armlinux.org.uk>
Date:   Fri, 3 Nov 2023 11:37:44 +0000
From:   "Russell King (Oracle)" <linux@...linux.org.uk>
To:     James Morse <james.morse@....com>
Cc:     linux-pm@...r.kernel.org, loongarch@...ts.linux.dev,
        linux-acpi@...r.kernel.org, linux-arch@...r.kernel.org,
        linux-kernel@...r.kernel.org, linux-arm-kernel@...ts.infradead.org,
        linux-riscv@...ts.infradead.org, kvmarm@...ts.linux.dev,
        x86@...nel.org, Salil Mehta <salil.mehta@...wei.com>,
        Jean-Philippe Brucker <jean-philippe@...aro.org>,
        jianyong.wu@....com, justin.he@....com
Subject: Re: [RFC PATCH v2 15/35] ACPI: processor: Add support for processors
 described as container packages

On Wed, Sep 13, 2023 at 04:38:03PM +0000, James Morse wrote:
> ACPI has two ways of describing processors in the DSDT. Either as a device
> object with HID ACPI0007, or as a type 'C' package inside a Processor
> Container.

I'm struggling with the reference to a "type 'C' package inside a
Processor Container".

ACPI 6.0, which introduced the Processor Container, says: "This optional
device is a container object that acts much like a bus node in a
namespace. It may contain child objects that are either processor devices
or other processor containers"

For "Processor device":

"For more information on the declaration of the processor device object,
see Section 19.6.30, "Device (Declare Device Package).""

which leads one to the Device() object, not the Processor() object.
It also states:

"A Device definition for a processor is declared using the ACPI0007
hardware identifier (HID)."

My understanding from this is that Processor() is not allowed to be
used within a Processor Container, only Device()s with _HID of
ACPI0007 are permitted.

In light of this, please could you clarify your first sentence, as it
seems to be contrary to what is stated in ACPI 6.x specs. Thanks.

-- 
RMK's Patch system: https://www.armlinux.org.uk/developer/patches/
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