Date: Wed, 8 Aug 2001 13:49:37 -0300 (BRST) From: Rik van Riel <riel@conectiva.com.br> To: craig <craiglei@pasia.com.cn> Cc: <tlambert2@mindspring.com>, <freebsd-hackers@FreeBSD.ORG> Subject: Re: Why page enable in Kernel space? Message-ID: <Pine.LNX.4.33L.0108081347120.1439-100000@duckman.distro.conectiva> In-Reply-To: <002001c11fab$19acaca0$051a0a0a@fd.com>
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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
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