Date: Thu, 9 Apr 2015 11:58:08 -0500 (CDT) From: "Valeri Galtsev" <galtsev@kicp.uchicago.edu> To: "Adrian Chadd" <adrian@freebsd.org> Cc: Pierre-Yves =?iso-8859-1?Q?P=C3=A9neau?= <pierre-yves.peneau@lip6.fr>, FreeBSD Questions <freebsd-questions@freebsd.org> Subject: Re: How FreeBSD manage more than 4GB on 32 bits architecture Message-ID: <55353.128.135.70.2.1428598688.squirrel@cosmo.uchicago.edu> In-Reply-To: <CAJ-Vmo=e1F1rHRW82r5uwJ5f-vOhZ1qKMbSsM4E0aomzQ=4=UQ@mail.gmail.com> References: <5526408F.1090005@asim.lip6.fr> <20150409114941.692910293a8120de4dafd400@yahoo.es> <20150409114906.6dd4379c@archlinux> <55264DC5.9070606@asim.lip6.fr> <55267A63.4040503@qeng-ho.org> <55269509.1080103@asim.lip6.fr> <CAJ-Vmo=e1F1rHRW82r5uwJ5f-vOhZ1qKMbSsM4E0aomzQ=4=UQ@mail.gmail.com>
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On Thu, April 9, 2015 11:19 am, Adrian Chadd wrote: > Hi! > > This sounds... very exciting. I'd start by taking a look at how PAE > works - you may be able to reuse all those pieces and just implement > more than the 4 bits of physical address space. The interesting bits > of PAE aren't just the extension of the physical addresses, but all > the management of mapping things into virtual address space as > required. The only problem with all these exercises is: on 32 bit CPU box a single process still can only have 4GB of address space (according to my definitely not deep enough knowledge of kernel)... Just my $0.02. Valeri > > I haven't looked at the MIPS side of things though. IIRC, on MIPS32 we > only implement up to what the direct map KSEG supports, so a little > PAE ish work would be required there to make things work right. > > So, I'd start by looking at how PAE on i386 works. I think there's a > little bit of KVA exhaustion going on in -HEAD with i386 PAE that can > be fixed with a little bit of attention. The rest of the basic PAE > stuff should still work fine. Then if you need it for MIPS, you'll > need to sketch out how you expect PAE to work on MIPS, and then make > up a project for that. :) > > > > -adrian > _______________________________________________ > freebsd-questions@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > To unsubscribe, send any mail to > "freebsd-questions-unsubscribe@freebsd.org" > ++++++++++++++++++++++++++++++++++++++++ Valeri Galtsev Sr System Administrator Department of Astronomy and Astrophysics Kavli Institute for Cosmological Physics University of Chicago Phone: 773-702-4247 ++++++++++++++++++++++++++++++++++++++++
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