From owner-freebsd-arm@FreeBSD.ORG Sun Dec 30 23:21:32 2012 Return-Path: Delivered-To: freebsd-arm@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 5B268CBC for ; Sun, 30 Dec 2012 23:21:32 +0000 (UTC) (envelope-from freebsd@damnhippie.dyndns.org) Received: from duck.symmetricom.us (duck.symmetricom.us [206.168.13.214]) by mx1.freebsd.org (Postfix) with ESMTP id 020558FC14 for ; Sun, 30 Dec 2012 23:21:27 +0000 (UTC) Received: from damnhippie.dyndns.org (daffy.symmetricom.us [206.168.13.218]) by duck.symmetricom.us (8.14.5/8.14.5) with ESMTP id qBUNLRlP079157 for ; Sun, 30 Dec 2012 16:21:27 -0700 (MST) (envelope-from freebsd@damnhippie.dyndns.org) Received: from [172.22.42.240] (revolution.hippie.lan [172.22.42.240]) by damnhippie.dyndns.org (8.14.3/8.14.3) with ESMTP id qBUNLO48084917; Sun, 30 Dec 2012 16:21:24 -0700 (MST) (envelope-from freebsd@damnhippie.dyndns.org) Subject: Re: What is this nand thing? From: Ian Lepore To: Brett Wynkoop In-Reply-To: <20121230180340.031a5945@ivory.wynn.com> References: <20121230180340.031a5945@ivory.wynn.com> Content-Type: text/plain; charset="us-ascii" Date: Sun, 30 Dec 2012 16:21:24 -0700 Message-ID: <1356909684.54953.81.camel@revolution.hippie.lan> Mime-Version: 1.0 X-Mailer: Evolution 2.32.1 FreeBSD GNOME Team Port Content-Transfer-Encoding: 7bit Cc: freebsd-arm@freebsd.org X-BeenThere: freebsd-arm@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Porting FreeBSD to the StrongARM Processor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 30 Dec 2012 23:21:32 -0000 On Sun, 2012-12-30 at 18:03 -0500, Brett Wynkoop wrote: > Greeting- > > What is this nand that I am reading about on the list? I have a > feeling it is not a NAND GATE we are speaking of. > > -Brett > Nand flash storage. It's the same stuff that's in an sdcard or a usb thumb drive. Some embedded systems have the bare storage chip on the board, without the microcontrollers found in sdcards et. al. The nand subsystem in freebsd is an in-kernel implementation of what those microcontrollers do (ecc calculations, managing bad blocks, in general the sort of thing that makes a bare chip into a mass storage device). The nandfs is a filesystem specially tailored for the needs of nand storage (and that's really about all I know about it; I'm unclear on how it stores its metadata and how the garbage collection stuff works). -- Ian