From mboxrd@z Thu Jan  1 00:00:00 1970
From: Sergey Yanovich <ynvich@gmail.com>
Subject: Re: [PATCH v2] wait while adding MMC host to ensure root mounts
Date: Thu, 14 Mar 2013 15:57:56 +0400
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To: Namjae Jeon <linkinjeon@gmail.com>
Cc: Chris Ball <cjb@laptop.org>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, Ulf Hansson <ulf.hansson@linaro.org>, Linus Walleij <linus.walleij@linaro.org>, Jaehoon Chung <jh80.chung@samsung.com>, linux-kernel@vger.kernel.org, linux-mmc@vger.kernel.org

On 14/03/13 08:08, Namjae Jeon wrote:> 2013/3/14, Sergey Yanovich <ynvich@gmail.com>:
>> Kernel panic - not syncing: VFS: Unable to mount root fs on
>> unknown-block(0,0)

> Have you ever tried to use rootwait or rootdelay on command line ?
> If no, You can use them.

Those options work. However, they introduce a delay in the range of hundreds milliseconds and seconds respectively. They delay is not required. If a cards is present, mmc_rescan will return synchronously with card initialized.

prepare_namespace() uses wait_for_device_probe(). The latter assumes that all "known devices" have initialized by the time it returns. MMC is not currently delivering on the assumptions. It will with the patch applied.