From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pl0-f70.google.com (mail-pl0-f70.google.com [209.85.160.70]) by kanga.kvack.org (Postfix) with ESMTP id 643B56B000C for ; Wed, 14 Feb 2018 22:44:54 -0500 (EST) Received: by mail-pl0-f70.google.com with SMTP id x2so12215335plv.16 for ; Wed, 14 Feb 2018 19:44:54 -0800 (PST) Date: Wed, 14 Feb 2018 22:44:44 -0500 From: joe.korty@concurrent-rt.com Subject: Re: [PATCH 00/31 v2] PTI support for x86_32 Message-ID: <20180215034444.GA18849@zipoli.concurrent-rt.com> Reply-To: "Joe Korty" References: <1518168340-9392-1-git-send-email-joro@8bytes.org> <20180209191112.55zyjf4njum75brd@suse.de> <20180210091543.ynypx4y3koz44g7y@angband.pl> <20180211105909.53bv5q363u7jgrsc@angband.pl> <6FB16384-7597-474E-91A1-1AF09201CEAC@gmail.com> <0C6EFF56-F135-480C-867C-B117F114A99F@amacapital.net> <20180214104342.GA12209@amd> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180214104342.GA12209@amd> Sender: owner-linux-mm@kvack.org List-ID: To: Pavel Machek Cc: Andy Lutomirski , int-list-linux-mm@kvack.orglinux-mm@kvack.org On Wed, Feb 14, 2018 at 11:43:42AM +0100, Pavel Machek wrote: > We have just found out that majority of 64-bit machines are broken in > rather fundamental ways (Spectre) and Intel does not even look > interested in fixing that (because it would make them look bad on > benchmarks). > > Even when the Spectre bug is mitigated... this looks like can of worms > that can not be closed. > > OTOH -- we do know that there are non-broken machines out there, > unfortunately they are mostly 32-bit :-). Removing support for > majority of working machines may not be good idea... > > [And I really hope future CPUs get at least option to treat cache miss > as a side-effect -- thus disalowed during speculation -- and probably > option to turn off speculation altogether. AFAICT, it should "only" > result in 50% slowdown -- or that was result in some riscv > presentation.] Or, future CPU designs introduce shadow caches and shadow TLBs which only speculation loads and sees and which become real only if and whend the resultant speculative calculations become real. Joe -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org