From: "H. Peter Anvin" <hpa@zytor.com>
To: Dave Hansen <dave@sr71.net>, linux-kernel@vger.kernel.org
Cc: bp@alien8.de, 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 09:37:57 -0700 [thread overview]
Message-ID: <53A46365.6090101@zytor.com> (raw)
In-Reply-To: <53A4619C.8020100@sr71.net>
On 06/20/2014 09:30 AM, Dave Hansen wrote:
> On 06/20/2014 09:23 AM, H. Peter Anvin wrote:
>> On 06/20/2014 09:17 AM, Dave Hansen wrote:
>>>> Today, we assume that all 64-bit cpus have X86_FEATURE_MP. It
>>>> should be in the REQUIRED_MASK so that we do not need the #undef
>>>> trick for it.
>> I don't think we enforce that the MP bit is set in CPUID, though.
>> Non-AMD processors will typically not set this bit at all, so the
>> feature validation code would have to be modified to know to not require
>> this bit.
>
> Ahh, OK. I'll drop this.
>
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?
-hpa
next prev parent reply other threads:[~2014-06-20 16:38 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 [this message]
2014-06-20 17:43 ` Borislav Petkov
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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