linux-kernel - Re: [RFC PATCH 22/22] x86/fpu/xstate: Introduce boot-parameters for control some state component support

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Message-ID: <cd1c42b1-dbb2-4f8a-7398-8359163adcc2@intel.com>
Date:   Fri, 2 Oct 2020 10:26:31 -0700
From:   Dave Hansen <dave.hansen@...el.com>
To:     Andy Lutomirski <luto@...nel.org>,
        "Chang S. Bae" <chang.seok.bae@...el.com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...nel.org>, Borislav Petkov <bp@...e.de>,
        X86 ML <x86@...nel.org>, Len Brown <len.brown@...el.com>,
        jing2.liu@...el.com, "Ravi V. Shankar" <ravi.v.shankar@...el.com>,
        LKML <linux-kernel@...r.kernel.org>,
        "open list:DOCUMENTATION" <linux-doc@...r.kernel.org>
Subject: Re: [RFC PATCH 22/22] x86/fpu/xstate: Introduce boot-parameters for
 control some state component support

On 10/2/20 10:15 AM, Andy Lutomirski wrote:
>> "xstate.enable=0x6000" will enable AMX on a system that does NOT have AMX
>> compiled into XFEATURE_MASK_USER_SUPPORTED (assuming the kernel is new
>> enough to support this feature).
> This sounds like it will be quite confusing to anyone reading the
> kernel code to discover that a feature that is not "SUPPORTED" is
> nonetheless enabled.
Yeah, if we do this, XFEATURE_MASK_USER_SUPPORTED needs a name change
for sure.