Date: Wed, 8 Aug 2001 09:40:27 +0800 From: "craig" <craiglei@pasia.com.cn> To: <tlambert2@mindspring.com> Cc: <freebsd-hackers@FreeBSD.ORG> Subject: Why page enable in Kernel space? Message-ID: <002001c11fab$19acaca0$051a0a0a@fd.com>
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[-- Attachment #1 --] In general a address in a process is just a linear address which refer to physical address indirectly by page directory. This is reasonable in user space. However is it necessary to do such thing in kernel? It is sure to have penalty when converting a linear address to physical thing. Is it worth doing such thing in kernel. 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? craiglei [-- Attachment #2 --] <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META content="text/html; charset=gb2312" http-equiv=Content-Type> <META content="MSHTML 5.00.2614.3500" name=GENERATOR> <STYLE></STYLE> </HEAD> <BODY bgColor=#ffffff> <DIV><FONT size=2>In general a address in a process is just a linear address which refer to physical address indirectly </FONT></DIV> <DIV><FONT size=2>by page directory. This is reasonable in user space. However is it necessary to do such thing in kernel?</FONT></DIV> <DIV><FONT size=2>It is sure to have penalty when converting a linear address to physical thing. Is it worth doing such</FONT></DIV> <DIV><FONT size=2>thing</FONT><FONT size=2> in kernel. </FONT></DIV> <DIV><FONT size=2></FONT> </DIV> <DIV><FONT size=2>I think the performance is the most important in kernel, other thing is second. I remember in </FONT></DIV> <DIV><FONT size=2>linux linear address is real physical address in kernel space(is it true?). Why freebsd does not do in the same way?</FONT></DIV> <DIV> </DIV> <DIV> </DIV> <DIV><FONT size=2>craiglei</FONT></DIV> <DIV> </DIV></BODY></HTML>
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