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    SubjectRe: [RFC PATCH V2 13/22] x86/intel_rdt: Support schemata write - pseudo-locking core
    On Tue, 27 Feb 2018, Thomas Gleixner wrote:
    > On Mon, 26 Feb 2018, Reinette Chatre wrote:
    > > Moving to "exclusive" mode it appears that, when enabled for a resource
    > > group, all domains of all resources are forced to have an "exclusive"
    > > region associated with this resource group (closid). This is because the
    > > schemata reflects the hardware settings of all resources and their
    > > domains and the hardware does not accept a "zero" bitmask. A user thus
    > > cannot just specify a single region of a particular cache instance as
    > > "exclusive". Does this match your intention wrt "exclusive"?
    >
    > Interesting question. I really did not think about that yet.

    Actually we could solve that problem similar to the locked one and share
    most of the functionality:

    mkdir group
    echo exclusive > mode
    echo L3:0 > restrict

    and for locked:

    mkdir group
    echo locksetup > mode
    echo L2:0 > restrict
    echo 'L2:0=0xf' > schemata
    echo locked > mode

    The 'restrict' file (feel free to come up with a better name) is only
    available/writeable in exclusive and locksetup mode. In case of exclusive
    mode it can contain several domains/resources, but in locked mode its only
    allowed to contain a single domain/resource.

    A write to schemata for exclusive or locksetup mode will apply the
    exclusiveness restrictions only to the resources/domains selected in the
    'restrict' file.

    Thanks,

    tglx

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