Date: Wed, 31 Jan 2018 18:44:55 +0200 From: Konstantin Belousov <kostikbel@gmail.com> To: "Bjoern A. Zeeb" <bzeeb-lists@lists.zabbadoz.net> Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r328625 - in head/sys: amd64/amd64 amd64/ia32 amd64/include dev/cpuctl i386/i386 x86/include x86/x86 Message-ID: <20180131164455.GR97752@kib.kiev.ua> In-Reply-To: <FF98ADF0-829E-419B-89C3-9717F62CD4A7@lists.zabbadoz.net> References: <201801311436.w0VEaRrZ030839@repo.freebsd.org> <FF98ADF0-829E-419B-89C3-9717F62CD4A7@lists.zabbadoz.net>
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On Wed, Jan 31, 2018 at 02:56:24PM +0000, Bjoern A. Zeeb wrote: > On 31 Jan 2018, at 14:36, Konstantin Belousov wrote: > > > Author: kib > > Date: Wed Jan 31 14:36:27 2018 > > New Revision: 328625 > > URL: https://svnweb.freebsd.org/changeset/base/328625 > > > > Log: > > IBRS support, AKA Spectre hardware mitigation. > > > For existing processors, you need a microcode update which adds IBRS > > CPU features, and to manually enable it by setting the > > tunable/sysctl > > hw.ibrs_disable to 0. Current status can be checked in sysctl > > hw.ibrs_active. The mitigation might be inactive if the CPU feature > > Can you change the tunable/sysctl to hw.ibrs_enable[d] (and toggle the > default setting along). This is done consistently with the hw.clflush_disable. Anyway, the intent is that the knob will be used for disabling, since defaults are going to be changed in the near future. > I find it highly confusing to have two different sysctls ???disable??? > and ???active??? and a lot > of people (and cultures) have trouble with the double negative. > Also the ???enable[d]??? variant seems to be pre-dominant in the kernel. > > Also can we spell IBRS in the sysctl description as ???Indirect Branch > Restricted Speculation (IBRS)???? Will do in half a hour.
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