From owner-freebsd-hackers Thu Sep 10 19:35:48 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id TAA24269 for freebsd-hackers-outgoing; Thu, 10 Sep 1998 19:35:48 -0700 (PDT) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from tarsier.domain.net (tarsier.domain.net [204.107.140.8]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id TAA24228 for ; Thu, 10 Sep 1998 19:35:42 -0700 (PDT) (envelope-from eric@tarsier.domain.net) Received: (from eric@localhost) by tarsier.domain.net (8.8.7/8.8.5) id TAA27612; Thu, 10 Sep 1998 19:35:01 -0700 (PDT) Message-ID: <19980910193501.55698@tarsier.domain.net> Date: Thu, 10 Sep 1998 19:35:01 -0700 From: eric To: Dennis Cc: hackers@FreeBSD.ORG Subject: Re: Boot from Flash References: <199809102017.QAA01623@etinc.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 0.79e In-Reply-To: <199809102017.QAA01623@etinc.com>; from Dennis on Thu, Sep 10, 1998 at 04:30:36PM -0400 Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG On Thu, Sep 10, 1998 at 04:30:36PM -0400, Dennis wrote: > > Has anyone used the PC plug-in PCMCIA flash cards successfully with FreeBSD? > If so can you boot from it without a HD? I've done some work with this. Yes, you can boot off the flash card just as if it were a disk. However, there are some problems. Due to the nature of the flash memory, you more or less have to use it as read-only media (flash memory can only be written about 100k times before it becomes read-only) and if you have things writing to the flash all the time (even if it's just to update access times in the inodes when files are read) there are spots on the flash that will get "worn out" rather quickly, leading to filesystem corruption. So the trick is to have your flash boot disk mounted read only and then either have anything that needs to write write to ramdisk (which goes away when you reboot) or do something like mount a writable directory from an NFS server elsewhere. An ideal solution would be to have a ramdisk union-mounted on top of the read-only flash, and then as part of the shutdown procedure write the contents of the ramdisk over the flash once. Unfortunately you can't do this in freebsd because the union filesystem isn't usable. (you can mount it, but the kernel panics if you try to access anything in it) So that's the state of my knowledge of it... eric To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message