From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from lazybastard.de ([212.112.238.170] helo=longford.logfs.org) by bombadil.infradead.org with esmtps (Exim 4.68 #1 (Red Hat Linux)) id 1K0J1T-0007eo-IM for linux-mtd@lists.infradead.org; Sun, 25 May 2008 16:24:40 +0000 Date: Sun, 25 May 2008 18:24:26 +0200 From: =?utf-8?B?SsO2cm4=?= Engel To: Jamie Lokier Subject: Re: Support of removable MTD devices and other advanced features (follow-up from lkml) Message-ID: <20080525162426.GA14741@logfs.org> References: <20080524175647.GA7366@logfs.org> <346401.5675.qm@web36705.mail.mud.yahoo.com> <20080525072501.GA13140@logfs.org> <20080525133029.GA3599@shareable.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20080525133029.GA3599@shareable.org> Cc: linux-mtd@lists.infradead.org, Alex Dubov List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Sun, 25 May 2008 14:30:29 +0100, Jamie Lokier wrote: > Jörn Engel wrote: > > > Memorystick cards can be written page at a time, but only in progressive > > > fashion - only if all pages at lower offsets to the current page were written > > > before. This can be made to work as a useful optimization. > > > > The same limitation is true for some raw NAND chips as well. Afaik all > > of current MTD honors that limitation. > > That seems like it would cause uneven wear-levelling in some > situations. Specifically, each time you need to erase a block which > has not been completely written, because you need to write a > contiguous record larger than the remaining space. > > I don't know it was a physical requirement of some chips, thanks for > clarifying. The "progressive" limitation only concerns writes _within_ eraseblocks. It has no impact on wear leveling. Jörn -- If you're willing to restrict the flexibility of your approach, you can almost always do something better. -- John Carmack