Date: Thu, 04 Jan 2018 07:00:02 -0800 From: "Chris H" <bsd-lists@BSDforge.com> To: <freebsd-current@freebsd.org> Subject: Re: Intel CPU design flaw - FreeBSD affected? Message-ID: <39abfc53763a4a83142af49e2d56aa59@udns.ultimatedns.net> In-Reply-To: <b735d895-342c-9a7b-4aea-acc371f48c7e@freebsd.org>
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On Thu, 4 Jan 2018 15:33:46 +0100 "Stefan Esser" <se@freebsd.org> said > Am 04.01.18 um 12:56 schrieb Darren Reed: > > On 4/01/2018 11:51 AM, Mark Heily wrote: > >> On Jan 2, 2018 19:05, "Warner Losh" <imp@bsdimp.com> wrote: > >> > >> The register article says the specifics are under embargo still. That would > >> make it hard for anybody working with Intel to comment publicly on the flaw > >> and any mitigations that may be underway. It would be unwise to assume that > >> all the details are out until the embargo lifts. > >> > >> > >> Details of the flaws are now published at: > >> > >> https://meltdownattack.com > > > > The web page has both: meltdown and spectre. > > Most people are only talking about meltdown which doesn't hit AMD. > > spectre impacts *both* Intel and AMD. > > > > SuSE are making available a microcode patch for AMD 17h processors that > > disables branch prediction: > > > > https://lists.opensuse.org/opensuse-security-announce/2018-01/msg00004.html > > Disabling branch prediction will have a very noticeable effect on execution > speed in general (while split page tables only affect programs that perform > system calls at a high frequency). OUCH! That was the whole point of these; drop cores, and frequency, for huge cache lines, and branch prediction. You eliminate that branch prediction, and these become near useless. :-( Glad I waited, before getting one! > > I have not fully read the Meltdown and Spectre papers, yet, but I do assume, > that the attack at the branch prediction tries to counter KASLR, which we do > not support at all in FreeBSD. > > So, I guess, we do not have to bother with disabling of branch prediction in > FreeBSD for the time being? > > Regards, STefan --Chrishelp
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