From owner-freebsd-hackers Wed Aug 8 9:49:57 2001 Delivered-To: freebsd-hackers@freebsd.org Received: from perninha.conectiva.com.br (perninha.conectiva.com.br [200.250.58.156]) by hub.freebsd.org (Postfix) with ESMTP id C3A0537B40D for ; Wed, 8 Aug 2001 09:49:51 -0700 (PDT) (envelope-from riel@conectiva.com.br) Received: from burns.conectiva (burns.conectiva [10.0.0.4]) by perninha.conectiva.com.br (Postfix) with SMTP id 86B3238BD5 for ; Wed, 8 Aug 2001 13:49:44 -0300 (EST) Received: (qmail 8722 invoked by uid 0); 8 Aug 2001 16:48:52 -0000 Received: from duckman.distro.conectiva (HELO duckman.conectiva.com.br) (root@10.0.17.2) by burns.conectiva with SMTP; 8 Aug 2001 16:48:52 -0000 Received: from localhost (riel@localhost) by duckman.conectiva.com.br (8.11.4/8.11.3) with ESMTP id f78Gnb828080; Wed, 8 Aug 2001 13:49:43 -0300 X-Authentication-Warning: duckman.distro.conectiva: riel owned process doing -bs Date: Wed, 8 Aug 2001 13:49:37 -0300 (BRST) From: Rik van Riel X-X-Sender: To: craig Cc: , Subject: Re: Why page enable in Kernel space? In-Reply-To: <002001c11fab$19acaca0$051a0a0a@fd.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG On Wed, 8 Aug 2001, craig wrote: > I think the performance is the most important in kernel, other > thing is second. I remember in linux linear address is real > physical address in kernel space(is it true?). Why freebsd does > not do in the same way? 1) wouldn't you think things like reliability to be more important than performance? ;) 2) Linux uses a 1:1 mapping of physical memory for the bulk of kernel memory, with physical address 0 mapped at virtual address 0xc0000000 and using 4MB pages 3) FreeBSD does do something remarkably similar, except that FreeBSD, IIRC, seems to put more of its data in 4 kB pages so the system has more flexibility wrt. where to allocate the kernel data ? regards, Rik -- IA64: a worthy successor to the i860. http://www.surriel.com/ http://www.conectiva.com/ http://distro.conectiva.com/ To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message