From: Borislav Petkov <bp@alien8.de>
To: Dave Hansen <dave.hansen@intel.com>
Cc: Feng Tang <feng.tang@intel.com>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, "H . Peter Anvin" <hpa@zytor.com>,
Peter Zijlstra <peterz@infradead.org>,
x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [RFC PATCH] tools/x86: add kcpuid tool to show raw CPU features
Date: Wed, 2 Sep 2020 18:52:16 +0200 [thread overview]
Message-ID: <20200902165216.GB21537@zn.tnic> (raw)
In-Reply-To: <5ef17179-7557-b609-2e72-20caa1369d46@intel.com>
On Wed, Sep 02, 2020 at 09:25:17AM -0700, Dave Hansen wrote:
> Ugh. I hate text parsers. But, I do see what you're getting at.
That's why it'll be a simple one. Nothing fancy. I'm hoping the final
version would be somewhat readable to humans too.
> If we do this, I bet having each value on its own line, I bet this would
> be a bit less painful to parse. It'll be a _bit_ harder to read, but
> not really. Maybe:
>
> LEAF[07],SUBLEAF[00],EAX[31:0],max_value, Max input value for supported
> subleafs
> LEAF[07],SUBLEAF[00],EBX[ 0],FSGSBASE,
> RDFSBASE/RDGSBASE/WRFSBASE/WRGSBASE if 1.
> LEAF[07],SUBLEAF[00],EBX[ 1],TSC_ADJUST, IA32_TSC_ADJUST MSR is
> supported if 1.
> LEAF[07],SUBLEAF[00],EBX[ 2],SGX, Supports Intel® Software Guard
> Extensions (Intel® SGX Extensions) if 1.
Yeah, this was just a stupid example to start the conversation.
> I was *really* hoping that we could eventually feed kcpuid and the
> X86_FEATURE_* bits from the same source.
But X86_FEATURE_* won't be all bits in all CPUID leafs - only the ones the
kernel has enabled/use for/needs/...
Also you have CPUID fields which are multi-bit and which cannot be
X86_FEATURE_* things.
So you need a place which has the whole CPUID space and X86_FEATURE_*
simply cannot represent it all.
--
Regards/Gruss,
Boris.
https://people.kernel.org/tglx/notes-about-netiquette
next prev parent reply other threads:[~2020-09-02 16:52 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-27 7:49 [RFC PATCH] tools/x86: add kcpuid tool to show raw CPU features Feng Tang
2020-09-02 15:40 ` Borislav Petkov
2020-09-02 16:25 ` Dave Hansen
2020-09-02 16:52 ` Borislav Petkov [this message]
2020-09-02 17:18 ` Dave Hansen
2020-09-02 18:19 ` Borislav Petkov
2020-09-03 7:17 ` Feng Tang
2020-09-02 16:45 ` peterz
2020-09-02 16:52 ` Dave Hansen
2020-09-02 16:59 ` peterz
2020-09-02 16:55 ` Borislav Petkov
2020-09-02 17:01 ` peterz
-- strict thread matches above, loose matches on Subject: below --
2020-07-21 2:00 Feng Tang
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