From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark Rutland Subject: Re: [PATCH ] arm64: cpuinfo: Add "model name" in /proc/cpuinfo for 64bit tasks also Date: Tue, 30 Aug 2016 11:52:18 +0100 Message-ID: <20160830105218.GD1223@leverpostej> References: <1472461345-28219-1-git-send-email-sumitg@nvidia.com> <20160830091935.GD5163@e104818-lin.cambridge.arm.com> <6a6e87361e7c4a1fab9639cb83276765@BGMAIL104.nvidia.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <6a6e87361e7c4a1fab9639cb83276765-gjLx+0+SZqK6sJks/06JalaTQe2KTcn/@public.gmane.org> Sender: linux-tegra-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Sumit Gupta Cc: Catalin Marinas , "linux-arm-kernel-IAPFreCvJWM7uuMidbF8XUB+6BGkLq7r@public.gmane.org" , "linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "yang.shi-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org" , "steve.capper-QSEj5FYQhm4dnm+yROfE0A@public.gmane.org" , "suzuki.poulose-5wv7dgnIgG8@public.gmane.org" , "will.deacon-5wv7dgnIgG8@public.gmane.org" , "julien.grall-5wv7dgnIgG8@public.gmane.org" , Bibek Basu , "james.morse-5wv7dgnIgG8@public.gmane.org" , "linux-tegra-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" List-Id: linux-tegra@vger.kernel.org On Tue, Aug 30, 2016 at 10:35:56AM +0000, Sumit Gupta wrote: > > > On Mon, Aug 29, 2016 at 02:32:25PM +0530, Sumit Gupta wrote: > > > Removed restriction of displaying model name for 32 bit tasks only. > > > Because of this Processor details were not displayed in "System > > > setting -> Details" in Ubuntu model name display is generic and can be > > > printed for 64 bit also. > > > > > > model name : ARMv8 Processor rev X (v8l) > > > > > > Signed-off-by: Sumit Gupta > > > > You didn't give a reason why this is needed. For 32-bit tasks, we did it for > > backwards compatibility with code checking for it. > > Within Ubuntu Home Screen "System setting -> details", processor details were coming as null. > It seems those details are retrieved from "model name" in /proc/cpuinfo and > because of check for 32 bit tasks only, "model name" was not getting displayed. It's worth noting that for arm64, we have never exposed a "model name" field for AArch64 tasks. i.e. the code was looking for something which did not exist to begin with. > On removing this check for model name, processor details are getting > displayed in Ubuntu Home Screen. > I think model name field is general and can be displayed irrespective > of compatibility. The "model name" field is somewhat useless, given we cannot query a usable string from the HW. We'd deliberately chosen to not expose it, to not give the impression that we would support trying to generate a string. We do expose the decoded MIDR_EL1 fields, which we can query from the HW. As above, this has never existed for arm64, and so 64-bit code relying on this non-existent field has never worked. It would be better to fix the code in question. Thanks, Mark.