From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matthew Wilcox Subject: Re: [PATCH 3/5] brd: Add getgeo to block ops Date: Wed, 27 Aug 2014 13:53:27 -0400 Message-ID: <20140827175327.GF3285@linux.intel.com> References: <53FDF7AD.5000709@plexistor.com> <53FDF919.6020006@plexistor.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Jens Axboe , Dmitry Monakhov , Ross Zwisler , linux-kernel , linux-fsdevel To: Boaz Harrosh Return-path: Content-Disposition: inline In-Reply-To: <53FDF919.6020006@plexistor.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org On Wed, Aug 27, 2014 at 06:28:25PM +0300, Boaz Harrosh wrote: > We set all hd_geometry members to 1, because this way fdisk > math will not try its crazy geometry math and get stuff totally wrong. > > I was trying to get some values that will make fdisk Want to align > first sector on 4K (like 8, 16, 20, ... sectors) but nothing worked, > I searched the net the math is not your regular simple multiplication > at all. > > If you managed to get these please tell me. I would love to solve > this. > > But for now we use 4k physical sectors for fixing fdisk alignment > issues, and setting these here to something that will not make > fdisk serve us with crazy numbers. Are you saying that fdisk ignores the 4k physical sectors (that you set up in patch 5/5) in favour of the geometry exposed here? That doesn't make sense to me, since it would misalign 4k-physical ATA drives if it did. I don't see anywhere else in the kernel reporting (1,1,1). The most common form to fake a geometry uses (64, 32, x), including SCSI.