From mboxrd@z Thu Jan 1 00:00:00 1970 From: alexanders83@web.de (Alexander Stein) Date: Sun, 22 Jan 2017 12:46:29 +0100 Subject: ARM64: Disabling warnings about deprecated armv8 instructions In-Reply-To: References: <1485072424.14066.2.camel@crowfest.net> <1485075528.14345.1.camel@crowfest.net> Message-ID: <22169925.OhJ0QcnbHM@localhost> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Sunday, January 22, 2017, 9:09:37 AM CET Ard Biesheuvel wrote: > On 22 January 2017 at 08:58, 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. > > > > I can double check, but I think the instructions are being emulated in > > hardware so they are just filling the log and slowing things down. > > > > [10685.558480] cp15barrier_handler: 197896 callbacks suppressed > > [10685.558487] "Xorg" (656) uses deprecated CP15 Barrier instruction at > > 0xf707fe9c > > [10685.558504] "Xorg" (656) uses deprecated CP15 Barrier instruction at > > 0xf7015944 > > [10685.558511] "Xorg" (656) uses deprecated CP15 Barrier instruction at > > 0xf7012494 > > [10685.558518] "Xorg" (656) uses deprecated CP15 Barrier instruction at > > 0xf70159b4 > > [10685.558527] "Xorg" (656) uses deprecated CP15 Barrier instruction at > > 0xf7011478 > > [10685.558533] "Xorg" (656) uses deprecated CP15 Barrier instruction at > > 0xf70114e8 > > [10685.558540] "Xorg" (656) uses deprecated CP15 Barrier instruction at > > 0xf7015944 > > [10685.558547] "Xorg" (656) uses deprecated CP15 Barrier instruction at > > 0xf7012494 > > [10685.558553] "Xorg" (656) uses deprecated CP15 Barrier instruction at > > 0xf70159b4 > > [10685.558560] "Xorg" (656) uses deprecated CP15 Barrier instruction at > > 0xf7011478 > > [10685.559179] compat_setend_handler: 1078 callbacks suppressed > > [10685.559188] "systemd-journal" (138) uses deprecated setend > > instruction at 0xf76a66f4 > > [10685.559196] "systemd-journal" (138) uses deprecated setend > > instruction at 0xf76a6bd8 > > [10685.559209] "systemd-journal" (138) uses deprecated setend > > instruction at 0xf76a66f4 > > [10685.559216] "systemd-journal" (138) uses deprecated setend > > instruction at 0xf76a6bd8 > > [10685.559231] "systemd-journal" (138) uses deprecated setend > > instruction at 0xf76a66f4 > > [10685.559237] "systemd-journal" (138) uses deprecated setend > > instruction at 0xf76a6bd8 > > [10685.559246] "systemd-journal" (138) uses deprecated setend > > instruction at 0xf76a66f4 > > [10685.559253] "systemd-journal" (138) uses deprecated setend > > instruction at 0xf76a6bd8 > > [10685.559269] "systemd-journal" (138) uses deprecated setend > > instruction at 0xf76a66f4 > > [10685.559276] "systemd-journal" (138) uses deprecated setend > > instruction at 0xf76a6bd8 > > You can disable the emulation by doing > > echo 2 >/proc/sys/abi/setend > echo 2 >/proc/sys/abi/cp15_barrier This reminds me of /proc/cpu/alignment to detect alignment problems in your application. Although armv6+ can handle unaligned access in most (!) cases you might want to trap thos cases. I would consider this a similar way. IMHO raspbian, still supporting raspberry pi 1 (armv6), should silence those warnings. Best regards, Alexander