From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lj1-x234.google.com (mail-lj1-x234.google.com [IPv6:2a00:1450:4864:20::234]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.bufferbloat.net (Postfix) with ESMTPS id 409CE3B2A4; Wed, 3 Oct 2018 14:32:27 -0400 (EDT) Received: by mail-lj1-x234.google.com with SMTP id 203-v6so6014106ljj.13; Wed, 03 Oct 2018 11:32:27 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=a8WLcLA+FKciSLFjkTMK9YgrAj75epQ1OeDBF33McnU=; b=gO4PRB9A56IAcCxKI+MQCeUOaj+PM4Lpn9GNlDYcbwQmFrVYPHdyvBI8BP/l/NnHQW b0rcXCq2acnrsygFhIavHZaoKhiWgqwtVI4rVLOEikA7TiqcP6pW9oOwMw5/pV4cU/FG BfGMYcZdBgJF0BMd4gpvDcfxZS/G2SejCAlXGMq04M/Wse9XEfrtyUcXDeIWXkPDrdkz CE6O0a28yeUDW45KLnRI8tq2ue9tHGmP0diRfqRCAevMtFbOyjAURJZoT4v/dxaRULwr xBrgLVrGL6/jjGb2DC4izUzNKD1Ba3/qLBDWOTAlZClEiJSw74MrqpIL9lqyMHz74EeC ljXw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:subject:from:in-reply-to:date:cc :content-transfer-encoding:message-id:references:to; bh=a8WLcLA+FKciSLFjkTMK9YgrAj75epQ1OeDBF33McnU=; b=T2aoc9bV84bKd1WU2Zz4EqoD3wf5H7L7iAW0AZrXzBcz8hXc5vcWXbPVP1U/b7e/7x 8Y7ri+NuSUXUofwB98zP3TEwvMg0WVfri/MNVoZuoMQSB4uNuJ/m+91n6T/ugrRDg6/f Epjx9AeECcWhf862U7oh2Hyk6/Gqam/O9dHEjwYa04YfTmRIOnVxJIbTlhiQJFX5BARi P830xjEW2ipqUa6Qrnj/bUxAMfvi1rt3kz29C8BvwIWy3mOLJlCSrkaQ8idUVhyikbZm OdPtbrHlH2kQEp3FTCDrS1wyeviEIMEpKe93qV/qAYPRlIGGSUWqSQq3VhkyqPvrszAk ABiQ== X-Gm-Message-State: ABuFfoglX1ysM4VBn2giLmQnqRp8CSEZEVJtnVv7/KqgAEWxStujHJeQ mDq89fGrgQZ2PtwddqXNzoI= X-Google-Smtp-Source: ACcGV62idhbp+pta+t5rKEy1othicgiTGCJ2PkS6BDOQ7ulH0B4wQIxX4IcCGNjvHnxE5qL/cvY2yA== X-Received: by 2002:a2e:6805:: with SMTP id c5-v6mr2023675lja.41.1538591546004; Wed, 03 Oct 2018 11:32:26 -0700 (PDT) Received: from jonathartonsmbp.lan (83-245-238-10-nat-p.elisa-mobile.fi. [83.245.238.10]) by smtp.gmail.com with ESMTPSA id p21-v6sm472916lfc.5.2018.10.03.11.32.24 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 03 Oct 2018 11:32:25 -0700 (PDT) Content-Type: text/plain; charset=utf-8 Mime-Version: 1.0 (Mac OS X Mail 11.5 \(3445.9.1\)) From: Jonathan Morton In-Reply-To: <87va6j9b97.fsf@toke.dk> Date: Wed, 3 Oct 2018 21:32:23 +0300 Cc: Dave Taht , Mikael Abrahamsson , Cake List , cerowrt-devel@lists.bufferbloat.net Content-Transfer-Encoding: quoted-printable Message-Id: <7DF1B2AE-37DD-4C08-A3A0-2890FAD0CE27@gmail.com> References: <1D2079D5-3BA8-4968-AD5A-990AFA3A7698@heistp.net> <87va6j9b97.fsf@toke.dk> To: =?utf-8?Q?Toke_H=C3=B8iland-J=C3=B8rgensen?= X-Mailer: Apple Mail (2.3445.9.1) Subject: Re: [Cerowrt-devel] [Cake] apu2 sqm/htb issue + a minor win for speeding up fq_codel itself X-BeenThere: cerowrt-devel@lists.bufferbloat.net X-Mailman-Version: 2.1.20 Precedence: list List-Id: Development issues regarding the cerowrt test router project List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 03 Oct 2018 18:32:27 -0000 > On 3 Oct, 2018, at 8:43 pm, Toke H=C3=B8iland-J=C3=B8rgensen = wrote: >=20 > I don't suppose 18.06 enables any of the SPECTRE mitigations (was that > an issue on ARM)? That depends on the ARM core involved. Most of them in CPE devices (eg. = Cortex-A5/7/53) have in-order execution engines, so should be immune - = but it's not inconceivable that some of the mitigations are enabled = regardless. The WRT1200AC uses the Marvell 88F6820 which has a pair of Cortex-A9 = cores. These are mildly out-of-order engines which would be at least = theoretically vulnerable to Spectre v1, but that is not a kernel-level = exploit. According to = https://www.techarp.com/guides/complete-meltdown-spectre-cpu-list/4/#arm = the Cortex-A9 is also vulnerable to Spectre v2 which is the = branch-predictor poisoning attack, for which kernel-level mitigations = may be appropriate. It is however immune to Meltdown. I'm not familiar with precisely what mitigations are now in use on ARM. = I am however certain that, on a device running only trustworthy code = (ie. not running a Web browser), mitigating Spectre is unnecessary. If = an attacker gets into a position to exploit it, he's already compromised = the device enough to run a botnet anyway. - Jonathan Morton