linux-kernel - Re: [PATCH v4 22/22] x86/fpu/xstate: Introduce boot-parameters to control state component support

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Message-ID: <4862AEE9-1819-43A7-BF95-C02DB6E2D06D@intel.com>
Date:   Sun, 21 Feb 2021 20:10:42 +0000
From:   "Bae, Chang Seok" <chang.seok.bae@...el.com>
To:     Randy Dunlap <rdunlap@...radead.org>
CC:     Borislav Petkov <bp@...e.de>, "luto@...nel.org" <luto@...nel.org>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "mingo@...nel.org" <mingo@...nel.org>,
        "x86@...nel.org" <x86@...nel.org>,
        "Brown, Len" <len.brown@...el.com>,
        "Hansen, Dave" <dave.hansen@...el.com>,
        "Liu, Jing2" <jing2.liu@...el.com>,
        "Shankar, Ravi V" <ravi.v.shankar@...el.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "linux-doc@...r.kernel.org" <linux-doc@...r.kernel.org>
Subject: Re: [PATCH v4 22/22] x86/fpu/xstate: Introduce boot-parameters to
 control state component support

On Feb 21, 2021, at 11:30, Randy Dunlap <rdunlap@...radead.org> wrote:
> Can we tell people (in this Doc file) where to look up the values that can be
> used in xstate.enable and xstate.disable?

Perhaps add something like this with the change below:
    “See comment before function fpu__init_parse_early_param() in
     arch/x86/kernel/fpu/init.c."

/*
 * The kernel parameter "xstate.enable='mask'" and "xstate.disable='mask'" have a
 * mask value in a subset of XFEATURE_MASK_CONFIGURABLE.
 *
 * The longest parameter is 22 octal number characters with '0' prefix and an extra
 * '\0' for termination.
 */
#define MAX_XSTATE_MASK_CHARS   24

/**
 * fpu__init_parse_early_param() - parse the xstate kernel parameters
 *
 * Parse them early because fpu__init_system() is executed before
 * parse_early_param().
 */
static void __init fpu__init_parse_early_param(void)

Thanks,
Chang