From owner-freebsd-mips@FreeBSD.ORG Tue Jun 8 06:27:11 2010 Return-Path: Delivered-To: mips@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 6422C1065672 for ; Tue, 8 Jun 2010 06:27:11 +0000 (UTC) (envelope-from juli@clockworksquid.com) Received: from mail-pz0-f183.google.com (mail-pz0-f183.google.com [209.85.222.183]) by mx1.freebsd.org (Postfix) with ESMTP id 3AB198FC13 for ; Tue, 8 Jun 2010 06:27:11 +0000 (UTC) Received: by pzk13 with SMTP id 13so125296pzk.13 for ; Mon, 07 Jun 2010 23:27:10 -0700 (PDT) Received: by 10.115.67.11 with SMTP id u11mr12391393wak.196.1275978429460; Mon, 07 Jun 2010 23:27:09 -0700 (PDT) MIME-Version: 1.0 Sender: juli@clockworksquid.com Received: by 10.114.241.2 with HTTP; Mon, 7 Jun 2010 23:26:49 -0700 (PDT) In-Reply-To: References: <4C07E07B.9060802@cs.rice.edu> <4C09345F.9040300@cs.rice.edu> <4C0D2BEA.6060103@cs.rice.edu> <4C0D3F40.2070101@cs.rice.edu> <20100607202844.GU83316@deviant.kiev.zoral.com.ua> <4C0D64B7.7060604@cs.rice.edu> From: Juli Mallett Date: Mon, 7 Jun 2010 23:26:49 -0700 X-Google-Sender-Auth: 6pDhNxRUj1yqPWlFlFNvBJkE49Q Message-ID: To: "C. Jayachandran" Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Cc: mips@freebsd.org Subject: Re: svn commit: r208589 - head/sys/mips/mips X-BeenThere: freebsd-mips@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Porting FreeBSD to MIPS List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 08 Jun 2010 06:27:11 -0000 On Mon, Jun 7, 2010 at 23:13, C. Jayachandran wr= ote: > On Tue, Jun 8, 2010 at 9:43 AM, Juli Mallett wrote= : >> Do you intend to support o32 kernels in your port indefinitely? =A0I >> wonder whether this work is just stopgap until the systems which have >> large amounts of RAM can just use n64 kernels. > > I think the page table work will be needed for o32 and n32, and I > would like to support one of them as the preferred 32bit mode for our > port. OK. > BTW, n32 with >4GB RAM can be supported with XKPHYS for page table > entries. The options there would be either special allocator for the > segtab (11+9+12 addr space split), or to use special allocator for all > the page table pages (10+10+12 split). Yeah, but we have a disinterest in supporting n32 kernels in base because it breaks assumptions in so many parts of the kernel, so I think the most reasonable expectation for base is to support o32 and n64, and to strongly prefer n64 for systems where it's more appropriate. >>=A0At least on Octeon it >> seems to me that n64-only is the right answer if at all possible, >> since there are really a lot of parts of the kernel that just can't >> reasonably work otherwise (use of rman_get_virtual with io ports, for >> instance.) > > Not sure I understand this part - I thought pmap_mapdev() would handle > these - but I may be mistaken. There's nothing pmap_mapdev can do on an o32 kernel with 32-bit PTEs for a physical address >2^36. (There are rather a lot of those on Octeon.) Juli.