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Subject: Re: Intel hardware bug
From: Eric McCorkle <eric@metricspace.net>
To: Brett Glass <brett@lariat.org>, =?UTF-8?Q?Dag-Erling_Sm=c3=b8rgrav?=
 <des@des.no>, Erich Dollansky <freebsd.ed.lists@sumeritec.com>
Cc: "freebsd-security@freebsd.org" <freebsd-security@freebsd.org>,
 "Ronald F. Guilmette" <rfg@tristatelogic.com>
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Date: Thu, 4 Jan 2018 12:06:22 -0500
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On 01/04/2018 12:03, Eric McCorkle wrote:

> You could block meltdown, I suppose, by making the entire
> kernel address space absolutely forbidden under penalty of an
> uncatchable signal.

Actually, scratch that; it doesn't work.  The caches are still affected,
and could be measured by another core.

I suppose you could attempt to flush them upon killing a process in this
way, but you still have a window, so it's only a probabilistic defense.