lkml.org 
[lkml]   [2020]   [May]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: [PATCH v4 1/3] arch/x86: Update config and kernel doc for MPK feature on AMD
    From
    Date
    On 5/12/20 4:58 PM, Babu Moger wrote:
    > +config X86_MEMORY_PROTECTION_KEYS
    > + # Both Intel and AMD platforms support "Memory Protection Keys"
    > + # feature. So add a generic option X86_MEMORY_PROTECTION_KEYS
    > + # and set the option whenever X86_INTEL_MEMORY_PROTECTION_KEYS
    > + # is set. This is to avoid the confusion about the feature
    > + # availability on AMD platforms. Also renaming the old option
    > + # would cause the user an extra prompt during the kernel
    > + # configuration. So avoided changing the old config name.
    > + def_bool X86_INTEL_MEMORY_PROTECTION_KEYS

    Hi Babu,

    I made a request earlier for an end date (or version) to be included
    here. I believe that appeared in one of your earlier versions, but it
    was removed in later ones.

    Was there a reason for that?

    I'd really prefer to put some kind of expiration date on the config
    option. It will outlive us all otherwise.

    > Memory Protection Keys for Userspace (PKU aka PKEYs) is a feature
    > which is found on Intel's Skylake "Scalable Processor" Server CPUs.
    > -It will be avalable in future non-server parts.
    > +It will be available in future non-server parts. Also, AMD64
    > +Architecture Programmer’s Manual defines PKU feature in AMD processors.

    I actually worked pretty hard to make that sentence useful to Linux
    users. Instead of forcing them to imply that it will be available on
    future AMD CPUs, can we just come out and say it? Can we give any more
    information to our users?

    Naming the AMD manual in which the feature is defined doesn't really
    help our users. Let's not waste the bytes on it.

    How about:

    Memory Protection Keys for Userspace (PKU aka PKEYs) is a
    feature which is found on Intel's Skylake (and later) "Scalable
    Processor" Server CPUs. It will be avalable in future non-
    server Intel parts and future AMD parts.

    Any clarity you can add, such as to say what AMD is doing for server vs.
    client would be nice.

    BTW, when I first submitted pkeys, I didn't have any statement like this
    in the changelog or documentation. Ingo, I think, asked for it and I
    worked with folks inside Intel to figure out how much we could say
    publicly about our plans. A similar effort from AMD would be much
    appreciated here.

    \
     
     \ /
      Last update: 2020-05-13 17:10    [W:2.525 / U:0.000 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site