From: Borislav Petkov <bp@alien8.de>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Dave Hansen <dave@sr71.net>,
linux-kernel@vger.kernel.org, x86@kernel.org,
Andi Kleen <ak@linux.intel.com>
Subject: Re: [RFC][PATCH 3/3] x86: make MP a required-feature on 64-bit
Date: Fri, 20 Jun 2014 19:43:45 +0200 [thread overview]
Message-ID: <20140620174345.GD11391@pd.tnic> (raw)
In-Reply-To: <53A46365.6090101@zytor.com>
On Fri, Jun 20, 2014 at 09:37:57AM -0700, H. Peter Anvin wrote:
> We probably should just the cpu_has_mp macro entirely. All it is used
> for is printing a warning in amd_k7_smp_check().
>
> Andi, Borislav -- as far as I can tell, we have *never* enforced this on
> the 64-bit kernel, although we have enforced it on 64-bit processors
> running the 32-bit kernel. We should either enforce it on both or just
> drop it. What is your opinion?
Well, my AMD CPUID guide says CPUID Fn8000_0001_EDX[19] is reserved,
i.e. that X86_FEATURE_MP bit will be probably cleared.
And so it is, on my F15h AMD it is not set:
eax in: 0x80000001, eax = 00600f20 ebx = 10000000 ecx = 01ebbfff edx = 2fd3fbff
^
----------|
So I don't think we should enforce it on 64-bit.
I guess we can leave the check in amd_k7_smp_check() though but remove that
nasty cpu_has_mp macro and do static_cpu_has() instead.
My 2¢ only.
--
Regards/Gruss,
Boris.
Sent from a fat crate under my desk. Formatting is fine.
--
next prev parent reply other threads:[~2014-06-20 17:43 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-20 16:17 [RFC][PATCH 1/3] x86: introduce disabled-features Dave Hansen
2014-06-20 16:17 ` [RFC][PATCH 2/3] x86: add more disabled features Dave Hansen
2014-06-20 16:17 ` [RFC][PATCH 3/3] x86: make MP a required-feature on 64-bit Dave Hansen
2014-06-20 16:23 ` H. Peter Anvin
2014-06-20 16:30 ` Dave Hansen
2014-06-20 16:37 ` H. Peter Anvin
2014-06-20 17:43 ` Borislav Petkov [this message]
2014-06-20 17:47 ` H. Peter Anvin
2014-06-20 18:05 ` Borislav Petkov
2014-06-20 18:16 ` Dave Jones
2014-06-20 18:48 ` Borislav Petkov
2014-06-20 18:54 ` H. Peter Anvin
2014-06-20 20:00 ` Borislav Petkov
2014-06-20 20:22 ` H. Peter Anvin
2014-06-20 20:35 ` Borislav Petkov
2014-06-20 17:50 ` H. Peter Anvin
2014-06-20 18:15 ` Borislav Petkov
2014-06-20 18:57 ` H. Peter Anvin
2014-06-20 20:37 ` Borislav Petkov
2014-06-23 6:11 ` Andi Kleen
2014-06-20 16:20 ` [RFC][PATCH 1/3] x86: introduce disabled-features H. Peter Anvin
2014-06-20 17:20 ` Dave Hansen
2014-06-20 20:40 ` Dave Hansen
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