Date: Thu, 2 Aug 2001 14:57:15 -0400 (EDT) From: Kenneth Wayne Culver <culverk@wam.umd.edu> To: John Baldwin <jhb@FreeBSD.org> Cc: Rik van Riel <riel@conectiva.com.br>, Rik van Riel <riel@conectiva.com.br>, Terry Lambert <tlambert2@mindspring.com>, craig <craiglei@pasia.com.cn>, freebsd-hackers@FreeBSD.org Subject: Re: How to visit physical memory above 4G? Message-ID: <Pine.GSO.4.21.0108021456050.20844-100000@rac2.wam.umd.edu> In-Reply-To: <XFMail.010802115425.jhb@FreeBSD.org>
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On Thu, 2 Aug 2001, John Baldwin wrote: > > On 02-Aug-01 Kenneth Wayne Culver wrote: > > BUT, don't the motherboards also have to support this? And isn't it only > > supported through some wierd segmentation thing? > > > > KEn > > The motherboards do, yes, and they have. It's not segmentation. It's only in > the paging that this is done. Go to developer.intel.com and get the IA32 > manuals, specifially volume 3: system programming, then look for 'Physical > Address Extensions' and start reading. > Alright, I guess I will later, although I doubt I'll be able to make much use of it. I usually only read the docs for hardware I'm going to write a driver for. :-) Ken > > On Thu, 2 Aug 2001, John Baldwin wrote: > > > >> > >> On 02-Aug-01 Kenneth Wayne Culver wrote: > >> > Also, the PIII CAN'T natively support more than 4GB of ram. If a > >> > particular PIII motherboard supports this, then it's using some kind of > >> > wierd chipset that allows this to happen. 4GB is the limit with a 32 bit > >> > chip I believe; and the PIII is a 32-bit chip. > >> > > >> > Ken > >> > >> Go look at some Intel docs. P6 chips since the Pentium Pro (yes, before > >> Pentium II) have supported PAE which allows for a 36-bit physical address. > >> > >> -- > >> > >> John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/ > >> PGP Key: http://www.baldwin.cx/~john/pgpkey.asc > >> "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ > >> > > > > -- > > John Baldwin <jhb@FreeBSD.org> -- http://www.FreeBSD.org/~jhb/ > PGP Key: http://www.baldwin.cx/~john/pgpkey.asc > "Power Users Use the Power to Serve!" - http://www.FreeBSD.org/ > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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