From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pd0-x231.google.com ([2607:f8b0:400e:c02::231]) by bombadil.infradead.org with esmtps (Exim 4.80.1 #2 (Red Hat Linux)) id 1Y29wd-0006ys-8F for linux-mtd@lists.infradead.org; Sat, 20 Dec 2014 02:39:05 +0000 Received: by mail-pd0-f177.google.com with SMTP id ft15so2297531pdb.22 for ; Fri, 19 Dec 2014 18:38:42 -0800 (PST) From: Brian Norris To: Subject: [PATCH mtd-www 4/4] faq: ubi: note that CONFIG_MTD_NAND_VERIFY_WRITE is dead Date: Fri, 19 Dec 2014 18:38:26 -0800 Message-Id: <1419043106-16453-4-git-send-email-computersforpeace@gmail.com> In-Reply-To: <1419043106-16453-1-git-send-email-computersforpeace@gmail.com> References: <1419043106-16453-1-git-send-email-computersforpeace@gmail.com> Cc: Brian Norris , David Woodhouse , Artem Bityutskiy List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , RIP. Signed-off-by: Brian Norris --- faq/ubi.xml | 22 ++++++++++++++++++++-- 1 file changed, 20 insertions(+), 2 deletions(-) diff --git a/faq/ubi.xml b/faq/ubi.xml index 9b2165def9c3..f8c40f64044d 100644 --- a/faq/ubi.xml +++ b/faq/ubi.xml @@ -567,9 +567,27 @@ ubi.mtd=0,2048

If you have a 2048 bytes per NAND page device, and have CONFIG_MTD_NAND_VERIFY_WRITE enabled in your kernel, you will need -to turn it off. The code does not currently (as of 2.6.26) perform verification +to turn it off. The code did not currently (as of 2.6.26) perform verification of sub-page writes correctly. As UBI is one of the few users of sub-page -writes, not much else seems to be affected by this bug.

+writes, not much else seemed to be affected by this bug. In Linux 3.7, +CONFIG_MTD_NAND_VERIFY_WRITE was removed: + +
+commit 657f28f8811c92724db10d18bbbec70d540147d6
+Date:   Tue Aug 14 22:38:45 2012 -0400
+
+    mtd: kill MTD_NAND_VERIFY_WRITE
+
+    "Both UBI and JFFS2 are able to read verify what they wrote already.
+    There are also MTD tests which do this verification. So I think there
+    is no reason to keep this in the NAND layer, let alone wasting RAM in
+    the driver to support this feature. Besides, it does not work for sub-pages
+    and many drivers have it broken. It hurts more than it provides benefits."
+
+    So kill MTD_NAND_VERIFY_WRITE entirely.
+
+ +

-- 1.9.1