From: "H. Peter Anvin" <hpa@zytor.com>
To: Maciej Wieczor-Retman <m.wieczorretman@pm.me>,
Pawan Gupta <pawan.kumar.gupta@linux.intel.com>
Cc: tglx@kernel.org, peterz@infradead.org, xin@zytor.com,
maciej.wieczor-retman@intel.com, babu.moger@amd.com,
chang.seok.bae@intel.com, sohil.mehta@intel.com,
dave.hansen@linux.intel.com, jpoimboe@kernel.org,
elena.reshetova@intel.com, ak@linux.intel.com,
darwi@linutronix.de, bp@alien8.de, mingo@redhat.com,
x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v11 3/4] x86/cpu: Do a sanity check on required feature bits
Date: Fri, 27 Mar 2026 19:01:01 -0700 [thread overview]
Message-ID: <4389fd82-e5a3-487f-9166-5bd2f3a434e3@zytor.com> (raw)
In-Reply-To: <d3468280-e7a8-4dc6-b6e2-0499f3e7a4fc@zytor.com>
On 2026-03-27 18:52, H. Peter Anvin wrote:
>
> One thing that matters here is that these bitmaps are *already* accessed using
> bitop operations. Therefore, if this is a problem *here*, then it is a problem
> *everywhere*. The simplest way to deal with it is probably to require NCAPINTS
> and NBUGINTS to be even, even (pun intended) if that means a temporarily
> unused word at the end of the array. That doesn't even require any code
> changes, just a statement at the top of cpufeatures.h (see attached patch for
> an untested example.)
>
Untested indeed. I just realized this breaks cpufeaturemasks.awk:
# Note: this blithely assumes that each word has at least one
# feature defined in it; if not, something else is wrong!
-hpa
next prev parent reply other threads:[~2026-03-28 2:33 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-03-20 12:50 [PATCH v11 0/4] x86: Capability bits fix and required bits sanity check Maciej Wieczor-Retman
2026-03-20 12:50 ` [PATCH v11 1/4] x86/cpu: Clear feature bits disabled at compile-time Maciej Wieczor-Retman
2026-03-20 12:50 ` [PATCH v11 2/4] x86/cpu: Check if feature string is non-zero Maciej Wieczor-Retman
2026-03-23 14:24 ` Borislav Petkov
2026-03-23 15:52 ` Maciej Wieczor-Retman
2026-03-23 16:23 ` Borislav Petkov
2026-03-23 16:58 ` Maciej Wieczor-Retman
2026-03-23 17:51 ` Borislav Petkov
2026-03-23 18:11 ` Maciej Wieczor-Retman
2026-03-23 18:15 ` H. Peter Anvin
2026-03-20 12:50 ` [PATCH v11 3/4] x86/cpu: Do a sanity check on required feature bits Maciej Wieczor-Retman
2026-03-21 0:31 ` Pawan Gupta
2026-03-21 5:58 ` Maciej Wieczór-Retman
2026-03-23 18:16 ` Pawan Gupta
2026-03-23 18:33 ` Maciej Wieczor-Retman
2026-03-26 18:36 ` Maciej Wieczor-Retman
2026-03-26 19:04 ` Pawan Gupta
2026-03-26 19:11 ` Maciej Wieczor-Retman
2026-03-28 1:52 ` H. Peter Anvin
2026-03-28 2:01 ` H. Peter Anvin [this message]
2026-03-30 9:47 ` Maciej Wieczor-Retman
2026-03-30 10:09 ` Maciej Wieczor-Retman
2026-03-30 16:01 ` Pawan Gupta
2026-03-30 21:24 ` David Laight
2026-03-31 8:12 ` Maciej Wieczor-Retman
2026-03-31 13:29 ` Maciej Wieczor-Retman
2026-03-23 16:31 ` Borislav Petkov
2026-03-23 17:05 ` Maciej Wieczor-Retman
2026-03-23 17:55 ` Borislav Petkov
2026-03-23 18:43 ` H. Peter Anvin
2026-03-23 18:43 ` H. Peter Anvin
2026-03-23 19:19 ` Borislav Petkov
2026-03-23 20:24 ` H. Peter Anvin
2026-03-23 20:58 ` Borislav Petkov
2026-03-23 21:40 ` H. Peter Anvin
2026-03-23 21:50 ` Borislav Petkov
2026-03-23 21:56 ` Borislav Petkov
2026-03-23 22:03 ` H. Peter Anvin
2026-03-23 22:09 ` Borislav Petkov
2026-03-24 1:16 ` H. Peter Anvin
2026-03-20 12:50 ` [PATCH v11 4/4] x86/cpu: Clear feature bits whose dependencies were cleared Maciej Wieczor-Retman
2026-03-23 16:35 ` Borislav Petkov
2026-03-23 17:23 ` Maciej Wieczor-Retman
2026-03-23 17:59 ` Borislav Petkov
2026-03-23 18:18 ` Maciej Wieczor-Retman
2026-03-23 18:57 ` H. Peter Anvin
2026-03-23 19:30 ` Borislav Petkov
2026-03-25 9:33 ` Maciej Wieczor-Retman
2026-03-23 19:33 ` Ahmed S. Darwish
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