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From:   Zhenguo Yao <yaozhenguo1@gmail.com>
Date:   Wed, 23 Mar 2022 10:44:28 +0800
Message-ID: <CA+WzARn0St6+oxqnyxBjP0MgzmzBqGX79TvB3A7TAMA5R0Pbbw@mail.gmail.com>
Subject: Re: [PATCH v1] device-dax: Adding match parameter to select which
 driver to match dax devices
To:     Dan Williams <dan.j.williams@intel.com>
Cc:     Vishal L Verma <vishal.l.verma@intel.com>,
        Dave Jiang <dave.jiang@intel.com>,
        Linux NVDIMM <nvdimm@lists.linux.dev>,
        =?UTF-8?B?5aea5oyv5Zu9?= <yaozhenguo@jd.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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I thought about it carefully. Indeed, in my scenario(virtual machine which =
use
optane as DRAM), device assignment can be performed in userspace at very
early time after the system is started. This patch is not needed in my
scenario. Thank you for your reply.

Dan Williams <dan.j.williams@intel.com> =E4=BA=8E2022=E5=B9=B43=E6=9C=8823=
=E6=97=A5=E5=91=A8=E4=B8=89 10:01=E5=86=99=E9=81=93=EF=BC=9A
>
> On Mon, Feb 28, 2022 at 1:50 AM Zhenguo Yao <yaozhenguo1@gmail.com> wrote=
:
> >
> > device_dax driver always match dax devices by default. The other
> > drivers only match devices by dax_id. There are situations which
> > need kmem drvier match all the dax device at boot time. So
> > adding a parameter to support this function.
>
> What are the situations that happen at boot time that can't wait for
> initramfs or userspace to move the device assignment?