From owner-freebsd-chat Thu Apr 1 12:46:41 1999 Delivered-To: freebsd-chat@freebsd.org Received: from smtp01.primenet.com (smtp01.primenet.com [206.165.6.131]) by hub.freebsd.org (Postfix) with ESMTP id 949A514FD5 for ; Thu, 1 Apr 1999 12:46:38 -0800 (PST) (envelope-from tlambert@usr08.primenet.com) Received: (from daemon@localhost) by smtp01.primenet.com (8.8.8/8.8.8) id MAA24111; Thu, 1 Apr 1999 12:45:54 -0700 (MST) Received: from usr08.primenet.com(206.165.6.208) via SMTP by smtp01.primenet.com, id smtpd017625; Thu Apr 1 12:34:56 1999 Received: (from tlambert@localhost) by usr08.primenet.com (8.8.5/8.8.5) id MAA08863; Thu, 1 Apr 1999 12:34:46 -0700 (MST) From: Terry Lambert Message-Id: <199904011934.MAA08863@usr08.primenet.com> Subject: Re: FreeBSD is running out of time To: ksmm@threespace.com (The Classiest Man Alive) Date: Thu, 1 Apr 1999 19:34:45 +0000 (GMT) Cc: doconnor@gsoft.com.au, freebsd-chat@FreeBSD.ORG In-Reply-To: <199904011659.LAA24524@geek.grf.ov.com> from "The Classiest Man Alive" at Apr 1, 99 11:40:13 am X-Mailer: ELM [version 2.4 PL25] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-freebsd-chat@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.org > I just assumed that once we made a change to something as fundamental as > the architecture's word size that everything else built upon that > (including the filesystem structures) would follow suit. In other words, I > wasn't expecting that backward compatibility would be paramount after going > 64-bit. Nope. Try talking to a 21041 chip on the other side of a PCI bridge in anything except device register size units. Device drivers don't change because of memory bus size changes. Also note that on-disk structure sizes are chosen for their ability to be represented in integral multiples or fractions of a physical disk block. It is drastically easier to deal in terms of an atomic write to a single disk block (check out the FFS directory entry code to see what it would take to allow it to span two 512b disk blocks -- I've made the change for Unicode support... it's not pretty). Inodes are currently 128 bytes; the next integral fraction of a disk block is 256 bytes. Note that this would effectively double the amount of disk space that must be dedicated to inode storage, even though it meets the <= one disk block pseudo-requirement. Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-chat" in the body of the message