From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matt Fleming Subject: Re: [PATCH v8 0/4] SysFS driver for QEMU fw_cfg device Date: Wed, 3 Feb 2016 22:47:29 +0000 Message-ID: <20160203224729.GB15385@codeblueprint.co.uk> References: <1453990994-17801-1-git-send-email-somlo@cmu.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1453990994-17801-1-git-send-email-somlo-D+Gtc/HYRWM@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: "Gabriel L. Somlo" Cc: gregkh-hQyY1W1yCW8ekmWlsbkhG0B+6BGkLq7r@public.gmane.org, robh+dt-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org, pawel.moll-5wv7dgnIgG8@public.gmane.org, mark.rutland-5wv7dgnIgG8@public.gmane.org, ijc+devicetree-KcIKpvwj1kUDXYZnReoRVg@public.gmane.org, galak-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org, arnd-r2nGTMty4D4@public.gmane.org, lersek-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, ralf-6z/3iImG2C8G8FEW9MqTrA@public.gmane.org, rmk+kernel-lFZ/pmaqli7XmaaqVzeoHQ@public.gmane.org, eric-WhKQ6XTQaPysTnJN9+BGXg@public.gmane.org, hanjun.guo-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, zajec5-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, sudeep.holla-5wv7dgnIgG8@public.gmane.org, agross-sgV2jX0FEOL9JmXXK+q4OQ@public.gmane.org, linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, qemu-devel-qX2TKyscuCcdnm+yROfE0A@public.gmane.org, mst-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, imammedo-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, peter.maydell-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, leif.lindholm-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, ard.biesheuvel-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org, pbonzini-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, kraxel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, ehabkost-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org, luto-kltTT9wpgjJwATOyAt5JVQ@public.gmane.org, stefanha-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org, revol-GANU6spQydw@public.gmane.org, rth-hL46jP5Bxq7R7s880joybQ@public.gmane.org List-Id: devicetree@vger.kernel.org On Thu, 28 Jan, at 09:23:10AM, Gabriel L. Somlo wrote: > From: "Gabriel Somlo" > > Allow access to QEMU firmware blobs, passed into the guest VM via > the fw_cfg device, through SysFS entries. Blob meta-data (e.g. name, > size, and fw_cfg key), as well as the raw binary blob data may be > accessed. > > The SysFS access location is /sys/firmware/qemu_fw_cfg/... and was > selected based on overall similarity to the type of information > exposed under /sys/firmware/dmi/entries/... > > This functionality is primarily intended to serve as a host->guest > configuration data transfer mechanism that is both: > > - asynchronous: the host doesn't need to wait for the guest > to be ready to accept data (e.g., by starting > an agent daemon) > > - out-of-band: there is no need to commandeer a guest element > normally visible and available to the guest user > (e.g., kernel cmdline, mounting floppy/cdrom, etc.) > > QEMU now allows arbitrary fw_cfg blobs to be added via the command line, > so it would be nice to make them easy to retrieve from within the guest > OS, and the niceset and easiest way I can think of is > > cat /sys/firmware/qemu-fw-cfg/...//raw > > New since v7: > > - kbuild testbot complained about a warning on ia64, so limit > the availability of fw_cfg in Kconfig to only architectures > on which QEMU makes it available, which include: > > (ARM || ARM64 || PPC_PMAC || SPARC || X86) This is looking pretty good now. Does anyone have remaining objections before this gets merged?