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Received: by mail.messagingengine.com (Postfix) with ESMTPA; Mon, 25 Oct 2021 07:44:27 -0400 (EDT) Date: Mon, 25 Oct 2021 06:44:26 -0500 From: Patrick Williams To: Greg Kroah-Hartman Subject: Re: [PATCH 4/5] driver core: inhibit automatic driver binding on reserved devices Message-ID: References: <20211022020032.26980-1-zev@bewilderbeest.net> <20211022020032.26980-5-zev@bewilderbeest.net> <627101ee-7414-57d1-9952-6e023b8db317@gmail.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="WMSkWp2LRUvE4R2V" Content-Disposition: inline In-Reply-To: X-BeenThere: openbmc@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Development list for OpenBMC List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Zev Weiss , "Rafael J. Wysocki" , Kirti Wankhede , Jeremy Kerr , Rajat Jain , Frank Rowand , Jianxiong Gao , Dave Jiang , kvm@vger.kernel.org, Saravana Kannan , Mauro Carvalho Chehab , openbmc@lists.ozlabs.org, devicetree@vger.kernel.org, Konrad Rzeszutek Wilk , Alex Williamson , Rob Herring , Bhaskar Chowdhury , Thomas Gleixner , Andy Shevchenko , Andrew Jeffery , Cornelia Huck , linux-kernel@vger.kernel.org, Vinod Koul , dmaengine@vger.kernel.org Errors-To: openbmc-bounces+openbmc=archiver.kernel.org@lists.ozlabs.org Sender: "openbmc" --WMSkWp2LRUvE4R2V Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Mon, Oct 25, 2021 at 08:15:41AM +0200, Greg Kroah-Hartman wrote: > On Mon, Oct 25, 2021 at 12:38:08AM -0500, Frank Rowand wrote: > > On 10/23/21 3:56 AM, Greg Kroah-Hartman wrote: =20 > We have the bind/unbind ability today, from userspace, that can control > this. Why not just have Linux grab the device when it boots, and then > when userspace wants to "give the device up", it writes to "unbind" in > sysfs, and then when all is done, it writes to the "bind" file and then > Linux takes back over. >=20 > Unless for some reason Linux should _not_ grab the device when booting, > then things get messier, as we have seen in this thread. This is probably more typical on a BMC than atypical. The systems often re= quire the BMC (running Linux) to be able to reboot independently from the managed= host (running anything). In the example Zev gave, the BMC rebooting would rip a= way the BIOS chip from the running host. The BMC almost always needs to come up in a "I don't know what could possib= ly be going on in the system" state and re-discover where the system was left off. --=20 Patrick Williams --WMSkWp2LRUvE4R2V Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAABCAAdFiEEBGD9ii4LE9cNbqJBqwNHzC0AwRkFAmF2mJgACgkQqwNHzC0A wRmJPBAAoNL9YeFVlTkyknrYGSwY85ZsAwF7xpzpe7Nbgmp3MqcreyEnyh8esoB/ +6A0VSL9H0GmJw9y42l73Z/xpCB3rUhL2n/wxkJrjPVegvBMhmo+e90yCQWdAJUV Ymjp9IbYdKZ7P221L6NeHKUf/Abf0sSgTf15heDzPV7kArCqLy+NmIcETU+evWc/ aP0ViL7mm16HWarwIUsANMc6wGRdpKfpd0rFjhqbQODpH9Y5L/QlltN/wTOf9C1L nI8UZREc4/T4Nvo07a6idJ4/VjyV54Bk7DfOo1HWGBrUkb9oNzWj2LNNKIb8feYD +bPu1m7fy/9xI/FQ7PdH1+pg4b1WtTUXQmis5Ilz6oShB8Fi1W7Ci4jHAtaotQ0t 7ZJzCK4uQK8YwU8K8SXFpZPKpYFyZb5k/tUn5CApqup3khzanNxdhCU5pc/kQWU5 70OujLBbi1BLzA9s23hpBU/DXmy4uR/neWC8pwVExGQHp2gEzjA5A1dWTKiBJpjE 2Rv4w6fHyq/deLS0SaQfb3MTiNvIBqu3sNseAhDC5zafIlUntCEDjxdGzTJZSiIR GHIcXTP7/Zm4RrdYBkP1NQU8W6Ya8HOfETvH/e4Ml8WLhfoyO2UL+weD9ICR8HAV MqSnKA06xb3wl48+ITunDfcbxeB3KoH8NJb+rZQIX/qAQCp6Liw= =Gvsf -----END PGP SIGNATURE----- --WMSkWp2LRUvE4R2V--