From mboxrd@z Thu Jan 1 00:00:00 1970 From: mzoran@crowfest.net (Michael Zoran) Date: Sun, 22 Jan 2017 01:52:40 -0800 Subject: ARM64: Disabling warnings about deprecated armv8 instructions In-Reply-To: References: <1485072424.14066.2.camel@crowfest.net> <9647813.NZ2c5cYUSH@localhost> <1485075528.14345.1.camel@crowfest.net> <20170122170523.3b4b1235@xhacker> <1485077887.1308.2.camel@crowfest.net> Message-ID: <1485078760.1308.6.camel@crowfest.net> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Sun, 2017-01-22 at 09:43 +0000, Ard Biesheuvel wrote: > On 22 January 2017 at 09:38, Michael Zoran > wrote: > > On Sun, 2017-01-22 at 17:05 +0800, Jisheng Zhang wrote: > > > On Sun, 22 Jan 2017 00:58:48 -0800 Michael Zoran wrote: > > > > > > > On Sun, 2017-01-22 at 09:52 +0100, Alexander Stein wrote: > > > > > Hi Michael, > > > > > > > > > > On Sunday, January 22, 2017, 12:07:04 AM CET Michael Zoran > > > > > wrote: > > > > > > I'm not sure if this if the correct place to be asking > > > > > > this.???The > > > > > > RPI > > > > > > 3 running ARM64 is slowly reaching the point of being about > > > > > > to > > > > > > seriously run a 32 bit vender OS like Raspbian.??When > > > > > > running > > > > > > Raspbian, > > > > > > I'm seeing a very large number(thousands) of kernel log > > > > > > messages > > > > > > about > > > > > > deprecated instructions especially setend and barrier > > > > > > instuctions. > > > > > > This can be very annoying and is completely filling the > > > > > > kernel > > > > > > log. > > > > > > > > > > > > I'm considering submitting a patch to add a Kconfig option > > > > > > to > > > > > > disable > > > > > > these warnings with the default being to keep the warnings > > > > > > enabled.??I > > > > > > was wondering if such a patch could be seriously > > > > > > considered. > > > > > > > > > > Could you please provide an example of those warning an what > > > > > is > > > > > trigging > > > > > those? > > > > > > > > > > Thanks and best regards, > > > > > Alexander > > > > > > > > Sure, here is a snipped from dmesg.??I think this is happening > > > > because > > > > the entire Raspbian OS is compiled with a custom gcc compiler > > > > that > > > > is > > > > targeting arm6+VFP. > > > > > > IMHO, this is the root cause. I didn't see below warnings from > > > dmesg > > > with > > > armhf debian and ubuntu If the underlying HW is armv8 compatible, > > > it > > > doesn't make sense to target the compiler to armv6 > > > > > > > > > > Advanced users can install a different OS. Beginners can't and will > > need a single OS image for simple install. > > > > That single OS image can simply test for the presence of > /proc/sys/abi, and perform the writes if it is there. > > > Does anybody know if these instructions are detected at runtime? > > What do you mean by 'detected'? > > > I'm > > also looking into an issue with Mathmatica due to broken OS > > detection. > > It appears that arm64 is currently missing some of the CPU spoofing > > that happens on other architectures... > > > > Could you elaborate? What do you think should be there that isn't? I'm saying that when running a ELF32 executable, the system needs to fake the CPU architecture according to the uname system API and /proc/cpuinfo. Today, I run uname -a in Raspbian and I get aarch64. I want it to display arm6l or whatever to get Mathematica to load. I see some code to make this work on other architectures such as X86, but most of this appears to be unimplemented on arm64.