From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: ARC-Seal: i=1; a=rsa-sha256; t=1518103361; cv=none; d=google.com; s=arc-20160816; b=F2oXlm7BvBcqkE7k2CtoWKqlxql16R7Idem2yvgtvOLEv8mFpFWkkldJ13lRSxpJyE YRPwBVIyMqzaUuKp06gDov0h0nPktuSh967spwuI5gbT9iMaX6KJYqd1igs8Ox8DrsUv FET2LZfKm+Z8Zd+bMyMgwMQkrIrhWXZPYSLp2Ug6oqAkBOmFftbmMNE43HJWmkLW2pXs oJ7ZKHtDYDDoXOWMBVE73ZEbrWaLmPGkqL9Wky1Tj2jRk77hi7HyJD+eIUpHW5li/9gs /G5+9VhxwC+T/DS3qx588RLNtXYDq52DmHDcwhnJ4NRBVvMkiv0MdZXSTDQiohdGYBst rdtg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=cc:to:subject:message-id:date:from:references:in-reply-to:sender :mime-version:dkim-signature:arc-authentication-results; bh=X8wc6TAgtQHjGQYzrES1L2Ia676MyLNLpVAZhReTMH4=; b=jgnB3Hy7sDqXCjqvySMIi16ZWhXPAbt0bUG8tiwtOblVAGGKxEPODckFxldOXP+xTF G6WnoNULFSvtY0oIvGP7gMUDYA7GuuItaCehrFvOJlc6Mp52kQKDFQaJYvAHJOrwDVmd MjENmIRcBN1DqLIVDz/KnjvesMO0szLZ7i+cfdyL3oirzXpgh/sbUfMGi/gyG53jmwjd 6eIC1p9ozDuyTa+tsMebegSc+OJyeF41aGAY6lQTRVMtf2JKE9CgXMLGe+l02c3/h9GN v8MLxbwnRMIM7tWbfdU4iEeKpO7cgZcXjC6d/VxBBnU9qxplv8LS+XOsyAxf2ACii7Y+ yfoA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=PvJcT4ph; spf=pass (google.com: domain of arndbergmann@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=arndbergmann@gmail.com Authentication-Results: mx.google.com; dkim=pass header.i=@gmail.com header.s=20161025 header.b=PvJcT4ph; spf=pass (google.com: domain of arndbergmann@gmail.com designates 209.85.220.65 as permitted sender) smtp.mailfrom=arndbergmann@gmail.com X-Google-Smtp-Source: AH8x2276/7azXSKX8BA43fF6jQF2J1H4nfM5q6ZcS7H3jJgusQnK85cjH09JuJYb8tRZUN043wdXKLqVL2S6jwfzaCk= MIME-Version: 1.0 Sender: arndbergmann@gmail.com In-Reply-To: <20180208134908.4b516794@alans-desktop> References: <1517950494.3677.30.camel@infradead.org> <201802070918.18978.linux@rainbow-software.org> <20180208134908.4b516794@alans-desktop> From: Arnd Bergmann Date: Thu, 8 Feb 2018 16:22:40 +0100 X-Google-Sender-Auth: u0VHc2hMoQtvJK2CgP0dBk1Y2yA Message-ID: Subject: Re: [BUG] x86 : i486 reporting to be vulnerable to Meltdown/Spectre_V1/Spectre_V2 To: Alan Cox Cc: Ondrej Zary , whiteheadm@acm.org, David Woodhouse , Guenter Roeck , Greg Kroah-Hartman , Hugh Dickins , Dave Hansen , Jiri Kosina , Borislav Petkov , Kees Cook , Jamie Iles , Eduardo Valentin , Laura Abbott , Rik van Riel , Thomas Gleixner , Linux Kernel Mailing List Content-Type: text/plain; charset="UTF-8" X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: =?utf-8?q?1591354140743903681?= X-GMAIL-MSGID: =?utf-8?q?1591846750566295367?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Thu, Feb 8, 2018 at 2:49 PM, Alan Cox wrote: >> What about Pentium II and 3? I'm using 5 such machines (and also a Pentium >> MMX). I've tried a spectre test before and it wasn't reading anything useful. >> Don't know about meltdown. Is there a complete test program? (The web is so >> full of crap that even google can't find anything useful.) > > For x86 speculation came in (as far as I can tell) in > > AMD Am5x86 > Cyrix 5x86, but branch predictors are disabled by default according to > the docs > Cyrix 6x86, branch prediction on by default > Pentium Pro > > There are later processors that don't have speculation: Quark series, Nat > Semi/Cyrix Geode, earliest AMD geode (I think), some Intel Atom > processors. Wasn't Am5x86 just a 486 clone? AFAICT, speculation only came with the K6 (Am6x86 aka NexGen Nx6x86) All the Geode are apparently derived from Cyrix 5x86 (I always thought it was a 6x86, but the internet disagrees). For Geode GX, a specification update at [1] mentions a special procedure for enabling branch prediction, Geode LX apparently gets this right and always has branch prediction. > The more obscure ones - the Transmeta apparently may, the IDT Winchip > documentation strongly implies it doesn't The Winchip is what eventually turned into the VIA Nano, which does have speculative execution, but I don't think the earlier C3 and C7 did, they are much closer to the original Winchip design. Arnd [1] http://support.amd.com/TechDocs/31533E_gx_2.1_specupdate.pdf