From mboxrd@z Thu Jan 1 00:00:00 1970 Received: (from majordomo@localhost) by oss.sgi.com (8.11.2/8.11.3) id g15GoY427163 for linux-mips-outgoing; Tue, 5 Feb 2002 08:50:34 -0800 Received: from real.realitydiluted.com (real.realitydiluted.com [208.242.241.164]) by oss.sgi.com (8.11.2/8.11.3) with SMTP id g15GoWA27156 for ; Tue, 5 Feb 2002 08:50:32 -0800 Received: from localhost.localdomain ([127.0.0.1] helo=cotw.com) by real.realitydiluted.com with esmtp (Exim 3.22 #1 (Red Hat Linux)) id 16Y8na-0000JQ-00 for ; Tue, 05 Feb 2002 10:50:26 -0600 Message-ID: <3C600D4C.43CBA784@cotw.com> Date: Tue, 05 Feb 2002 10:50:20 -0600 From: "Steven J. Hill" Reply-To: sjhill@cotw.com X-Mailer: Mozilla 4.77 [en] (X11; U; Linux 2.4.17-xfs i686) X-Accept-Language: en MIME-Version: 1.0 To: linux-mips@oss.sgi.com Subject: What is the maximum physical RAM for a 32bit MIPS core? Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: owner-linux-mips@oss.sgi.com Precedence: bulk I am just trying to fill in some more MIPS knowledge here. With a 32-bit MIPS processor, we are forever limited to a userspace of 2GB in size thanks to the kuser region. kseg0/1 map the same 512MB of physical memory. kseg2 is 1GB in size and hence it could address another 1GB of RAM. So, is the maximum amount of RAM for a 32bit MIPS core: 1) 1.5GB = 0.5GB kseg0/1 + 1.0GB kseg2 2) 4.0GB = largest 32-bit address 3) Something larger than 4.0GB by adding fancy external HW logic Also, for choice #3, while it would be a hit in performance, could you use the fp registers for 64-bit pointers to address larger than 4.0GB? Thanks in advance. -Steve -- Steven J. Hill - Embedded SW Engineer