From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 985ABC4727F for ; Mon, 21 Sep 2020 22:52:58 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id EE9DA23A65 for ; Mon, 21 Sep 2020 22:52:57 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org EE9DA23A65 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=ucw.cz Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 60CAC6B00C6; Mon, 21 Sep 2020 18:52:57 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 59943900007; Mon, 21 Sep 2020 18:52:57 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 45DC26B00C8; Mon, 21 Sep 2020 18:52:57 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0050.hostedemail.com [216.40.44.50]) by kanga.kvack.org (Postfix) with ESMTP id 2F1A76B00C6 for ; Mon, 21 Sep 2020 18:52:57 -0400 (EDT) Received: from smtpin20.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id E29CF180AD802 for ; Mon, 21 Sep 2020 22:52:56 +0000 (UTC) X-FDA: 77288570352.20.voice07_5e113cd27148 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin20.hostedemail.com (Postfix) with ESMTP id BF472180C07AB for ; Mon, 21 Sep 2020 22:52:56 +0000 (UTC) X-HE-Tag: voice07_5e113cd27148 X-Filterd-Recvd-Size: 3930 Received: from jabberwock.ucw.cz (jabberwock.ucw.cz [46.255.230.98]) by imf45.hostedemail.com (Postfix) with ESMTP for ; Mon, 21 Sep 2020 22:52:56 +0000 (UTC) Received: by jabberwock.ucw.cz (Postfix, from userid 1017) id D6A341C0B8C; Tue, 22 Sep 2020 00:52:51 +0200 (CEST) Date: Tue, 22 Sep 2020 00:52:51 +0200 From: Pavel Machek To: Dave Hansen Cc: "Yu, Yu-cheng" , Randy Dunlap , x86@kernel.org, "H. Peter Anvin" , Thomas Gleixner , Ingo Molnar , linux-kernel@vger.kernel.org, linux-doc@vger.kernel.org, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-api@vger.kernel.org, Arnd Bergmann , Andy Lutomirski , Balbir Singh , Borislav Petkov , Cyrill Gorcunov , Dave Hansen , Eugene Syromiatnikov , Florian Weimer , "H.J. Lu" , Jann Horn , Jonathan Corbet , Kees Cook , Mike Kravetz , Nadav Amit , Oleg Nesterov , Peter Zijlstra , "Ravi V. Shankar" , Vedvyas Shanbhogue , Dave Martin , Weijiang Yang Subject: Re: [PATCH v12 1/8] x86/cet/ibt: Add Kconfig option for user-mode Indirect Branch Tracking Message-ID: <20200921225251.GB13299@amd> References: <20200918192312.25978-1-yu-cheng.yu@intel.com> <20200918192312.25978-2-yu-cheng.yu@intel.com> <20200918205933.GB4304@duo.ucw.cz> <019b5e45-b116-7f3d-f1f2-3680afbd676c@intel.com> <20200918214020.GF4304@duo.ucw.cz> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="vGgW1X5XWziG23Ko" Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: --vGgW1X5XWziG23Ko Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable Hi! > > +config X86_INTEL_BRANCH_TRACKING_USER > > + prompt "Intel Indirect Branch Tracking for user-mode"=20 >=20 > Take the "Intel " and "INTEL_" out, please. It will only cause us all > pain later if some of our x86 compatriots decide to implement this. Are other x86 manufacturers legally allowed to implement that? > > If the kernel is to be used only on older systems that do not support > > IBT, and the size of the binary is important, you can save 900 KB by > > disabling this feature. > >=20 > > Otherwise, if unsure, say Y. >=20 > 900k seems like a *lot*. Where the heck does that come from? >=20 > Also, comments like that don't age very well. Consider: >=20 > Support for this feature is only known to be present on Intel > processors released in 2020 or later. This feature is also > known to increase kernel text size substantially. >=20 > If unsure, say N. That is much better, thanks. Pavel --=20 (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blo= g.html --vGgW1X5XWziG23Ko Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iEYEARECAAYFAl9pLsMACgkQMOfwapXb+vJrcACfdEe0RXB3Ob0O3qo7vS+3J9EX tmQAoMBivI2SYhK1uaQoHu+xCvzD3BHu =QpK9 -----END PGP SIGNATURE----- --vGgW1X5XWziG23Ko--