From owner-freebsd-questions@FreeBSD.ORG Fri Apr 10 19:16:51 2015 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 7CBE37F2 for ; Fri, 10 Apr 2015 19:16:51 +0000 (UTC) Received: from mail-ig0-x230.google.com (mail-ig0-x230.google.com [IPv6:2607:f8b0:4001:c05::230]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 411A48AB for ; Fri, 10 Apr 2015 19:16:51 +0000 (UTC) Received: by igbqf9 with SMTP id qf9so5764782igb.1 for ; Fri, 10 Apr 2015 12:16:50 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:sender:in-reply-to:references:date:message-id:subject :from:to:cc:content-type; bh=6eKzfvXnNzrCQVoamXIqc7R+ejwJA1We9ECiG7XvRkM=; b=uN/+brs8JtFxhdPi6OHYArZ40eFuFcEip4wTFrd8JeXEJhMB00BoomCPN0QdlhcGhY iAM8NLOs6HtABtWn3ue+7pn4Xhvl4j+QDA2lk2yXKPDdLEfHQbvWjUlrhWpEkNcQjPel 9bgfEWrzmH3yMBkRyMh2KQr5F8Rz5++63BjdqIGEIvRFB3LzWNGruBlsnNerPHdxJ8Fy NDzwABr/xOFzWc0m+mSSUuEZEM+B3O10AGBwcA/RiZhCvv9VIzsZ/THFXt/aouV0UDhO 0zM2RKlcj5Vff4pzSFAfC7sLGQ+7VOf+Y3+6wEMIYpwEWDERHPwlLt7/Y0Q/vqJddvH+ 012g== MIME-Version: 1.0 X-Received: by 10.42.137.202 with SMTP id z10mr5717301ict.37.1428693410660; Fri, 10 Apr 2015 12:16:50 -0700 (PDT) Sender: adrian.chadd@gmail.com Received: by 10.36.17.194 with HTTP; Fri, 10 Apr 2015 12:16:50 -0700 (PDT) In-Reply-To: <20150410171240.770.qmail@ary.lan> References: <552794F7.60306@asim.lip6.fr> <20150410171240.770.qmail@ary.lan> Date: Fri, 10 Apr 2015 12:16:50 -0700 X-Google-Sender-Auth: hQqN5idV3fuWueA5RZLN95pWKV8 Message-ID: Subject: Re: How FreeBSD manage more than 4GB on 32 bits architecture From: Adrian Chadd To: John Levine Content-Type: text/plain; charset=UTF-8 Cc: Pierre-Yves.Peneau@lip6.fr, FreeBSD Questions X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 10 Apr 2015 19:16:51 -0000 Hi! Everyone - this is a research project. If they want to hack around with FreeBSD on a PAE style 32 bit system but massively parallel, please let them. If they hit the same walls as others have hit, hey, great. But they may come up with something novel. Pierre - thanks for looking into it. Yes, there's PAE support in FreeBSD. Yes, there's some NUMA domain awareness in FreeBSD. You're definitely not starting from scratch. I don't know of any PAE style awareness in the MIPS32 code; that would be a good place to start investigating. So please take a look at what PAE / i386 is doing and see if you can map that to vm and pmap management for MIPS32. It'd likely overlap a lot with how we would support > 256MB of RAM on MIPS32 - right now we just use the direct map setup for everything, and that's limited to the KSEG sizes of 256MB. -adrian