From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-fx0-f49.google.com ([209.85.161.49]) by bombadil.infradead.org with esmtp (Exim 4.72 #1 (Red Hat Linux)) id 1P0wHw-0005Ye-0j for linux-mtd@lists.infradead.org; Wed, 29 Sep 2010 13:01:37 +0000 Received: by fxm15 with SMTP id 15so515294fxm.36 for ; Wed, 29 Sep 2010 06:01:35 -0700 (PDT) Subject: Re: [PATCH] nandwrite: add --nobad to write bad blocks From: Artem Bityutskiy To: Iwo Mergler In-Reply-To: <4CA2B3E9.3030707@call-direct.com.au> References: <1284263480-31573-1-git-send-email-vapier@gentoo.org> <1284308851.1783.23.camel@brekeke> <1284358990.27765.154.camel@localhost> <1284441967.2084.18.camel@brekeke> <1285139570.7512.137.camel@localhost> <4CA2B3E9.3030707@call-direct.com.au> Content-Type: text/plain; charset="UTF-8" Date: Wed, 29 Sep 2010 15:59:33 +0300 Message-ID: <1285765173.2437.123.camel@localhost> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Cc: linux-mtd@lists.infradead.org, Mike Frysinger Reply-To: dedekind1@gmail.com List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, 2010-09-29 at 13:35 +1000, Iwo Mergler wrote: > The upshot of this is that blocks are marked as bad by the > manufacturer based on corner case testing. Like erasing at > high temperature / low voltage and reading back at low > temperature / high voltage. The manufacturer can also > access pads on the naked die that are not connected to pins > during packaging. Is only about letting you write to bad eraseblocks, not about erasing them. I assumed this cannot be used for marking bad eraseblocks as good back. The kernel does not have any protection against writing to bad eraseblocks, so I do not see why Mike cannot have this option. But speaking about erasing bad eraseblocks, which we also discussed, I think you have a good point - we should probably distinguish between factory-marked bad eraseblocks and user-marked. AFAIR, the OOB marker for them was even different, or in BBT, do not really remember. We probably can allow erasing user-marked bad eraseblocks and unmarking them. But we probably should not allow erasing factory-marked bad eraseblocks. But again, I'm not sure if it is possible to do, did not really think about this. But I think this particular patch from Mike is OK. -- Best Regards, Artem Bityutskiy (Артём Битюцкий)