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=-7.3 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham 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 C7844C43381 for ; Sun, 17 Feb 2019 20:44:32 +0000 (UTC) Received: from krantz.zx2c4.com (krantz.zx2c4.com [192.95.5.69]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 6189A2184A for ; Sun, 17 Feb 2019 20:44:32 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=tomli.me header.i=@tomli.me header.b="DLVURLEV" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6189A2184A Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=tomli.me Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=wireguard-bounces@lists.zx2c4.com Received: from krantz.zx2c4.com (localhost [IPv6:::1]) by krantz.zx2c4.com (ZX2C4 Mail Server) with ESMTP id 37d1ae62; Sun, 17 Feb 2019 20:35:55 +0000 (UTC) Received: from krantz.zx2c4.com (localhost [127.0.0.1]) by krantz.zx2c4.com (ZX2C4 Mail Server) with ESMTP id 7b5c2760 for ; Sun, 17 Feb 2019 20:35:52 +0000 (UTC) Received: from tomli.me (tomli.me [IPv6:2a00:1a28:1157:199::5a76]) by krantz.zx2c4.com (ZX2C4 Mail Server) with ESMTP id 0c82a6e9 for ; Sun, 17 Feb 2019 20:35:51 +0000 (UTC) Received: from tomli.me (localhost [127.0.0.1]) by tomli.me (OpenSMTPD) with ESMTP id a90cbc51; Sun, 17 Feb 2019 20:44:09 +0000 (UTC) X-HELO: localhost.localdomain Authentication-Results: tomli.me; auth=pass (login) smtp.auth=tomli Received: from Unknown (HELO localhost.localdomain) (2402:f000:1:1501:200:5efe:7b76:78da) by tomli.me (qpsmtpd/0.95) with ESMTPSA (DHE-RSA-CHACHA20-POLY1305 encrypted); Sun, 17 Feb 2019 20:44:09 +0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed; d=tomli.me; h=date:from:to:cc:subject:message-id:references:mime-version:content-type:in-reply-to; s=1490979754; bh=Ogd+io1yuXNPyMlAST8jZfAGC83VKH2oBe1YUV/hXDs=; b=DLVURLEVt25SJvoKAZBqeA916BW6xvl9QHxKSIE81XoA6ixOXr/tanwTwNixQRIQHJZ5upxs7JyMrzs5sMl5Cnxq++9SYPe/WDkR56jli6e0N0ntSqMEQU8wMU4KUP/SMaCmi8VS6HGY3/nfwA5Erco4qXU16d5Pm0jYEOvbfsfCF84jdlQ75vu8w8B6TZGEqdVP3gs7B+yfE9M8iXjrxU2uXwquKefX8N6v3RfJp2BnjBYofrrYuCyoYqEDAw7OkyyvyTxEvviQG24leWO6YxuegcMX3WwaM5dSTpqRa7Z3txxYuMSn94neEGQQpP9irGDAAOkOLNhSmvCqg3sJ8w== Date: Mon, 18 Feb 2019 04:44:02 +0800 From: Tom Li To: Roman Mamedov Subject: Re: Logical cores / SMT with WireGuard Message-ID: <20190217204401.GA26054@localhost.localdomain> References: <735c8b20-c92b-2403-1557-32187b130a8f@icloud.com> <20190217160136.6138076b@natsu> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190217160136.6138076b@natsu> User-Agent: Mutt/1.10.1 (2018-07-13) Cc: wireguard@lists.zx2c4.com X-BeenThere: wireguard@lists.zx2c4.com X-Mailman-Version: 2.1.15 Precedence: list List-Id: Development discussion of WireGuard List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: wireguard-bounces@lists.zx2c4.com Sender: "WireGuard" On Sun, Feb 17, 2019 at 04:01:36PM +0500, Roman Mamedov wrote: > On Thu, 14 Feb 2019 18:02:26 +0000 > Lee Yates wrote: > > Sorry, hit "send" before reading the rest of your message. > > > the router runs headless and is awkward to get a monitor to so I can access > > the BIOS. > > You can toggle it without needing the BIOS. > It is possible to disable SMT from grub, with Linux kernel boot arguments. > It even seems possible to disable/enable it without a reboot. > See https://www.golinuxhub.com/2018/01/how-to-disable-or-enable-hyper.html Hi all. The information provided by the original link is out-of-date, it works, but it's tedious and easy to make a mistake and disable the wrong logical CPU. The new Linux kernel with L1TF fixes has introduced a SMT kill switch, which is the standard interface to control SMT. It's located at /sys/devices/system/cpu/smt/control You can disable SMT by, echo "off" > /sys/devices/system/cpu/smt/control enable it by, echo "on" > /sys/devices/system/cpu/smt/control Or permanently disable it until reboot, echo "forceoff" > /sys/devices/system/cpu/smt/control. More information is available at, https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/admin-guide/l1tf.rst I hope it helps. Cheers, Tom Li _______________________________________________ WireGuard mailing list WireGuard@lists.zx2c4.com https://lists.zx2c4.com/mailman/listinfo/wireguard