From mboxrd@z Thu Jan 1 00:00:00 1970 From: Rob Herring Subject: Re: [PATCH v5.5] of/fdt: export fdt blob as /sys/firmware/fdt Date: Tue, 18 Nov 2014 17:11:26 -0600 Message-ID: References: <1415984735-32388-1-git-send-email-ard.biesheuvel@linaro.org> <20141118165145.4F6A8C40966@trevor.secretlab.ca> <20141118172545.GC14323@leverpostej> <20141118221103.4ECB3C40966@trevor.secretlab.ca> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Return-path: In-Reply-To: <20141118221103.4ECB3C40966-WNowdnHR2B42iJbIjFUEsiwD8/FfD2ys@public.gmane.org> Sender: devicetree-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Grant Likely Cc: Mark Rutland , Ard Biesheuvel , "leif.lindholm-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org" , "geoff.levand-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org" , "devicetree-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" , Ian Campbell List-Id: devicetree@vger.kernel.org On Tue, Nov 18, 2014 at 4:11 PM, Grant Likely wrote: > On Tue, 18 Nov 2014 17:25:45 +0000 > , Mark Rutland > wrote: >> On Tue, Nov 18, 2014 at 04:51:45PM +0000, Grant Likely wrote: >> > On Fri, 14 Nov 2014 18:05:35 +0100 >> > , Ard Biesheuvel >> > wrote: >> > > Create a new /sys entry '/sys/firmware/fdt' to export the FDT blob >> > > that was passed to the kernel by the bootloader. This allows userland >> > > applications such as kexec to access the raw binary. [...] >> > * It also helps with exposing the reserved map to userspace, but kexec >> > has done without that feature for years, and it is in the process of >> > being deprecated in favour of /reserved-memory anyway. >> >> This is the first I'd heard of the reserve map being deprecated, and >> we're going to have DTs with reserved map entries for a long time going >> forwards. > > Deprecated, not removed or disabled. It will still work pretty much > forever, but users should be encouraged to move to the reserve-memory > tree. I thought you had said reserve map was still the right way for memory the kernel should never touch. >> Can't we expose the header fields under something like >> /sys/firmware/devicetree/dtb-header/, parallel to the usual >> /sys/firmware/devicetree/base for nodes? > > We could do that too. > > Honestly though, I'm just unsure of what the best thing to do is. If you > and a few others tell me that, "no, exporting the raw dtb is the right > thing to do", then I'll be okay, merge the patch and sleep properly. I always sleep better when others can take the blame. What happens when we rev the dtb format? Is the ABI the blob or the format of the blob? I lean towards we should add this. This is providing what is "in the firmware" while /proc/devicetree provides the live tree state including overlays. Rob -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html