From mboxrd@z Thu Jan 1 00:00:00 1970 Subject: Re: [PATCH] MTD: fix dataflash 64-bit divisions From: Artem Bityutskiy To: David Brownell In-Reply-To: <200812170956.55539.david-b@pacbell.net> References: <1229532627.17960.37.camel@sauron> <200812170956.55539.david-b@pacbell.net> Content-Type: text/plain; charset=utf-8 Date: Thu, 18 Dec 2008 08:26:57 +0200 Message-Id: <1229581617.17960.63.camel@sauron> Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Cc: linux-mtd , David Woodhouse Reply-To: dedekind@infradead.org List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , On Wed, 2008-12-17 at 09:56 -0800, David Brownell wrote: > On Wednesday 17 December 2008, Artem Bityutskiy wrote: > > From: Artem Bityutskiy > > Date: Wed, 17 Dec 2008 19:42:38 +0200 > > Subject: [PATCH] MTD: fix dataflash 64-bit divisions > >=20 > > MTD has recently been upgraded for 64-bit support, see commit > > number 69423d99fc182a81f3c5db3eb5c140acc6fc64be in the > > mtd-2.6.git tree (git://git.infradead.org/mtd-2.6.git) >=20 > Hmm, in another thread I was just reading about how Linux > would only support the first 2 GBytes of a 4 GByte NAND > chip (Samsung MT29F16G08DAA) ... the updates to support > large pages were easy, but signed 32-bit offsets prevented > the full size from being recognized. Slightly older parts > integrated four dies with 2K pages, not two with 4KB ones, > and gave no trouble. Yeah, we still do not support 4KiB pages, and >2GiB NANDs. > Would this be part of a set of patches making 4 GByte > (and eventually, larger) NAND chips behave? Well, this patch does only part of the job - it changes in-kernel API. Yes, makes >4GiB NANDs behave, and we tested it with NAND simulator (nandsim). However, all the user-space interfaces are still 32-bit. And the interfaces are not extendible, so someone should invent completely new MTD interfaces. And to support 4KiB-page NANDs, which have 128bytes OOB, one needs to change user-space interfaces (ioctls), because they support 64-bit OOBs at max. On the other hand, I personally do not care about OOB support, because it is in general better to avoid any use of OOB. --=20 Best regards, Artem Bityutskiy (=D0=91=D0=B8=D1=82=D1=8E=D1=86=D0=BA=D0=B8=D0=B9 =D0=90= =D1=80=D1=82=D1=91=D0=BC)