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From:   Mark-PK Tsai <mark-pk.tsai@mediatek.com>
To:     <hch@infradead.org>
CC:     <agk@redhat.com>, <dm-devel@redhat.com>,
        <linux-arm-kernel@lists.infradead.org>,
        <linux-kernel@vger.kernel.org>,
        <linux-mediatek@lists.infradead.org>, <mark-pk.tsai@mediatek.com>,
        <matthias.bgg@gmail.com>, <snitzer@redhat.com>,
        <tequila.huang@mediatek.com>, <yj.chiang@mediatek.com>
Subject: Re: [PATCH] dm: add module parameter bdev_wait
Date:   Thu, 28 Oct 2021 13:49:46 +0800
Message-ID: <20211028054946.1524-1-mark-pk.tsai@mediatek.com>
In-Reply-To: <YXj37wXtN0wQqwZx@infradead.org>
References: <YXj37wXtN0wQqwZx@infradead.org>
MIME-Version: 1.0
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> > dm_early_create() fail if the target block device not found in
> > the late init stage.
> > The block device is created in mmc_rescan() which kernel do
> > it async by queue it into system_freezable_wq.
> > Add module param bdev_wait to support waiting the block device
> > ready before dm_early_create() like prepare_namespace() does.
>
> This adds a busy loop.  There is a reason why we usually set up
> stacking drivers from userspace, in that we have a working event
> system there.  So the answer is not to add further hacks to the
> in-kernel DM setup hack, but to stop using it.

Thanks for your kind reply.
But We want to use DM target as root device without adding an initramfs.
Is there any other way to do so?