From owner-freebsd-hackers Wed Jul 7 23:59:53 1999 Delivered-To: freebsd-hackers@freebsd.org Received: from mycenae.ilion.eu.org (mycenae.ilion.eu.org [203.35.206.129]) by hub.freebsd.org (Postfix) with ESMTP id E3B8414D21 for ; Wed, 7 Jul 1999 23:59:47 -0700 (PDT) (envelope-from patrykz@mycenae.ilion.eu.org) Received: from mycenae.ilion.eu.org (patrykz@localhost [127.0.0.1]) by mycenae.ilion.eu.org (8.9.2/8.9.2) with ESMTP id QAA17097; Thu, 8 Jul 1999 16:59:16 +1000 (EST) (envelope-from patrykz@mycenae.ilion.eu.org) Message-Id: <199907080659.QAA17097@mycenae.ilion.eu.org> To: Ville-Pertti Keinonen Cc: julian@whistle.com (Julian Elischer), hackers@FreeBSD.ORG Subject: Re: Bursting at the seams (was: Heh heh, humorous lockup) In-reply-to: Your message of "08 Jul 1999 09:47:32 +0300." <86oghnr62j.fsf@not.demophon.com> Date: Thu, 08 Jul 1999 16:59:16 +1000 From: Patryk Zadarnowski Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG > julian@whistle.com (Julian Elischer) writes: > > > we already use the gs register for SMP now.. > > what about the fs register? > > I vaguely remember that the different segments could be used to achieve > > this.... (%fs points to user space or something) > > You can't extend the address space that way, segments are all parts of > the single 4GB address space described by the page mapping. True, but you can reserve a part of the 4GB address space (say 128MB of it) for partitioning into tiny (say 8MB) address spaces (which are still flat, just small), for use by small processes, the idea being that all those small processes will than share a single page table without compromising on memory protection (the GDT is under full OS's control anyway), or the simplicity of a flat address space (virtual addresses still start at 0 and continue till the top of address space; the scheme is totally transparent.) patryk. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message