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    SubjectRe: [RFC PATCH v2 15/35] ACPI: processor: Add support for processors described as container packages
    On Thu, Sep 14, 2023 at 02:53:53PM +0100, Jonathan Cameron wrote:
    > On Wed, 13 Sep 2023 16:38:03 +0000
    > James Morse <james.morse@arm.com> 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. The ACPI processor driver probes CPUs described as devices, but
    > > not those described as packages.
    > >
    >
    > Specification reference needed...
    >
    > Terminology wise, I'd just refer to Processor() objects as I think they
    > are named objects rather than data terms like a package (Which include
    > a PkgLength etc)

    I'm not sure what kind of reference you want for the above. Looking in
    ACPI 6.5, I've found in 5.2.12:

    "Starting with ACPI Specification 6.3, the use of the Processor() object
    was deprecated. Only legacy systems should continue with this usage. On
    the Itanium architecture only, a _UID is provided for the Processor()
    that is a string object. This usage of _UID is also deprecated since it
    can preclude an OSPM from being able to match a processor to a
    non-enumerable device, such as those defined in the MADT. From ACPI
    Specification 6.3 onward, all processor objects for all architectures
    except Itanium must now use Device() objects with an _HID of ACPI0007,
    and use only integer _UID values."

    Also, there is:

    https://uefi.org/specs/ACPI/6.5/08_Processor_Configuration_and_Control.html#declaring-processors

    Unfortunately, using the search facility on that site to try and find
    Processor() doesn't work - it appears to strip the "()" characters from
    the search (which is completely dumb, why do search facilities do that?)

    > > The missing probe for CPUs described as packages creates a problem for
    > > moving the cpu_register() calls into the acpi_processor driver, as CPUs
    > > described like this don't get registered, leading to errors from other
    > > subsystems when they try to add new sysfs entries to the CPU node.
    > > (e.g. topology_sysfs_init()'s use of topology_add_dev() via cpuhp)
    > >
    > > To fix this, parse the processor container and call acpi_processor_add()
    > > for each processor that is discovered like this. The processor container
    > > handler is added with acpi_scan_add_handler(), so no detach call will
    > > arrive.
    > >
    > > Qemu TCG describes CPUs using packages in a processor container.
    >
    > processor terms in a processor container.

    Are you wanting this to be:

    "Qemu TCG describes CPUs using processor terms in a processor
    container."

    ? Searching the ACPI spec for "processor terms" (with or without quotes)
    only brings up results for "terms" - yet another reason to hate site-
    provided search facilities, I don't know why sites bother. :(

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