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=2Eorg> said > Am 04=2E01=2E18 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=2Ecom> wrote: > >> > >> The register article says the specifics are under embargo still=2E That = would > >> make it hard for anybody working with Intel to comment publicly on the= flaw > >> and any mitigations that may be underway=2E It would be unwise to assume= that > >> all the details are out until the embargo lifts=2E > >> > >> > >> Details of the flaws are now published at: > >> > >> https://meltdownattack=2Ecom > >=20 > > The web page has both: meltdown and spectre=2E > > Most people are only talking about meltdown which doesn't hit AMD=2E > > spectre impacts *both* Intel and AMD=2E > >=20 > > SuSE are making available a microcode patch for AMD 17h processors that > > disables branch prediction: > >=20 > > https://lists=2Eopensuse=2Eorg/opensuse-security-announce/2018-01/msg00004=2E= html >=20 > Disabling branch prediction will have a very noticeable effect on executi= on > speed in general (while split page tables only affect programs that perfo= rm > system calls at a high frequency)=2E OUCH! That was the whole point of these; drop cores, and frequency, for hug= e cache lines, and branch prediction=2E You eliminate that branch prediction, a= nd these become near useless=2E :-( Glad I waited, before getting one! >=20 > I have not fully read the Meltdown and Spectre papers, yet, but I do assu= me, > that the attack at the branch prediction tries to counter KASLR, which we= do > not support at all in FreeBSD=2E >=20 > So, I guess, we do not have to bother with disabling of branch prediction= in > FreeBSD for the time being? >=20 > Regards, STefan --Chris
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