From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dirk Behme Subject: Re: [PATCH 1/2] mmc: block: mmcblkN: use slot index instead of dynamic name index Date: Wed, 8 Aug 2012 08:12:22 +0200 Message-ID: <50220346.4030606@de.bosch.com> References: <1344237900-14815-1-git-send-email-dirk.behme@de.bosch.com> <8739402g1m.fsf@octavius.laptop.org> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <8739402g1m.fsf@octavius.laptop.org> Sender: linux-mmc-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="us-ascii"; format="flowed" To: Chris Ball Cc: "linux-mmc@vger.kernel.org" , "linaro-dev@lists.linaro.org" , "linux-embedded@vger.kernel.org" , Jassi Brar Hi Chris, On 06.08.2012 17:31, Chris Ball wrote: > Hi, > > On Mon, Aug 06 2012, Dirk Behme wrote: >> On embedded devices, often there is a combination of removable mmc >> devices (e.g. MMC/SD cards) and hard wired ones (e.g. eMMC). >> Depending on the hardware configuration, the 'mmcblkN' node might >> change if the removable device is available or not at boot time. >> >> E.g. if the removable device is attached at boot time, it might >> become mmxblk0. And the hard wired one mmcblk1. But if the removable >> device isn't there at boot time, the hard wired one will become >> mmcblk0. This makes it somehow difficult to hard code the root device >> to the non-removable device and boot fast. >> >> This change does simply associate 'N' of 'mmcblkN' with the slot index >> instead of the dynamic name index. The slot index is always the same, >> ensuring that the non-removable mmc device is associated always >> with the same mmcblkN. Independent of the availability of the removable >> one. > > I like this change in principle, Thanks :) > but doesn't it break boot for everyone > currently using e.g. root=/dev/mmcblk0p1 on slot index 2? That doesn't > sound like an acceptable regression. I'm not really an expert of the code in block.c. Could you imagine a change which has the same result we'd like to get with the proposed patch but doesn't have the regression you mention? Many thanks and best regards Dirk