linux-kernel - Re: [PATCH v3 21/21] x86/fpu/xstate: Introduce boot-parameters to control some state component support

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Message-ID: <3AB31479-2394-4BFF-B309-F692E9135CE0@intel.com>
Date:   Thu, 14 Jan 2021 21:31:19 +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 v3 21/21] x86/fpu/xstate: Introduce boot-parameters to
 control some state component support


> On Dec 23, 2020, at 10:37, Randy Dunlap <rdunlap@...radead.org> wrote:
> 
> On 12/23/20 7:57 AM, Chang S. Bae wrote:
>> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
>> index 44fde25bb221..a67ae04d43c5 100644
>> --- a/Documentation/admin-guide/kernel-parameters.txt
>> +++ b/Documentation/admin-guide/kernel-parameters.txt
>> @@ -6002,6 +6002,21 @@
>> 			which allow the hypervisor to 'idle' the guest on lock
>> 			contention.
>> 
>> +	xstate.enable=	[X86-64]
>> +	xstate.disable=	[X86-64]
>> +			The kernel is compiled with a default xstate bitmask --
>> +			enabling it to use the XSAVE hardware to efficiently
>> +			save and restore thread states on context switch.
>> +			xstate.enable allows adding to that default mask at
>> +			boot-time without recompiling the kernel just to support
>> +			the new thread state. (Note that the kernel will ignore
>> +			any bits in the mask that do not correspond to features
>> +			that are actually available in CPUID)  xstate.disable
> 
> 			                               CPUID.)
> 
>> +			allows clearing bits in the default mask, forcing the
>> +			kernel to forget that it supports the specified thread
>> +			state. When a bit set for both, the kernel takes
>> +			xstate.disable in a priority.
> 
> 			               as a priority.
> ?

Thank you. I fixed those typos in my tree.

Chang