Date: Mon, 13 Apr 2015 18:43:21 +0300 From: Konstantin Belousov <kostikbel@gmail.com> To: Benjamin Kaduk <bjkfbsd@gmail.com> Cc: "svn-src-head@freebsd.org" <svn-src-head@freebsd.org>, "svn-src-all@freebsd.org" <svn-src-all@freebsd.org>, "src-committers@freebsd.org" <src-committers@freebsd.org> Subject: Re: svn commit: r281495 - in head/sys: conf i386/i386 i386/include x86/acpica Message-ID: <20150413154321.GW2390@kib.kiev.ua> In-Reply-To: <CAJ5_RoBb%2BpPLW=-CPVdyCH%2BDnqAJyOA8BK5sei4zwKPz5BH0eg@mail.gmail.com> References: <201504131522.t3DFMkiE050257@svn.freebsd.org> <CAJ5_RoBb%2BpPLW=-CPVdyCH%2BDnqAJyOA8BK5sei4zwKPz5BH0eg@mail.gmail.com>
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On Mon, Apr 13, 2015 at 11:24:09AM -0400, Benjamin Kaduk wrote: > On Mon, Apr 13, 2015 at 11:22 AM, Konstantin Belousov <kib@freebsd.org> > wrote: > > > Author: kib > > Date: Mon Apr 13 15:22:45 2015 > > New Revision: 281495 > > URL: https://svnweb.freebsd.org/changeset/base/281495 > > > > Log: > > Add config option PAE_TABLES for the i386 kernel. It switches pmap to > > use PAE format for the page tables, but does not incur other > > consequences of the full PAE config. In particular, vm_paddr_t and > > bus_addr_t are left 32bit, and max supported memory is still limited > > by 4GB. > > > > The option allows to have nx permissions for memory mappings on i386 > > kernel, while keeping the usual i386 KBI and avoiding the kernel data > > sizing problems typical for the PAE config. > > > > Intel documented that the PAE format for page tables is available > > starting with the Pentium Pro, but it is possible that the plain > > Pentium CPUs have the required support (Appendix H). The goal is to > > enable the option and non-exec mappings on i386 for the GENERIC > > kernel. Anybody wanting a useful system on 486, have to reconfigure > > the modern i386 kernel anyway. > > > > Discussed with: alc, jhb > > Sponsored by: The FreeBSD Foundation > > MFC after: 2 weeks > > > > relnotes: yes? I do not see much use in the wide announcement. Right now, this is yet another kernel option. If the required benchmarking and some more old documentation spelunking is going to be done, so that the GENERIC is indeed switched to requiring PAE, then relnotes should indeed mention the change. Otherwise, I do not see why this could be interesting to a user who cannot read NOTES.
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