From mboxrd@z Thu Jan 1 00:00:00 1970 From: steve.capper@linaro.org (Steve Capper) Date: Fri, 14 Mar 2014 09:42:10 +0000 Subject: [PATCH v4] ARM: vDSO gettimeofday using generic timer architecture In-Reply-To: <1394734769-32760-1-git-send-email-nathan_lynch@mentor.com> References: <1394734769-32760-1-git-send-email-nathan_lynch@mentor.com> Message-ID: <20140314094209.GA27302@linaro.org> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thu, Mar 13, 2014 at 01:19:29PM -0500, Nathan Lynch wrote: > Provide fast userspace implementations of gettimeofday and > clock_gettime on systems that implement the generic timers extension > defined in ARMv7. This follows the example of arm64 in conception but > significantly differs in some aspects of the implementation (C vs > assembly, mainly). > > Clocks supported: > - CLOCK_REALTIME > - CLOCK_MONOTONIC > - CLOCK_REALTIME_COARSE > - CLOCK_MONOTONIC_COARSE > > This also provides clock_getres (as arm64 does). > > Note that while the high-precision realtime and monotonic clock > support depends on the generic timers extension, support for > clock_getres and coarse clocks is independent of the timer > implementation and is provided unconditionally. > > Run-time tested on OMAP5, Arndale, and i.MX6 using a patched glibc[1], > verifying that results from the vDSO are consistent with results from > the kernel. > > [1] RFC glibc patch here: > https://www.sourceware.org/ml/libc-alpha/2014-02/msg00680.html > > Signed-off-by: Nathan Lynch > Tested-by: Steve Capper > --- > > Steve, since I made some minor changes from v3, re-testing on your > Arndale would be very much appreciated and would keep the changelog > technically honest :-) Hi Nathan, Sure :-), I've given this another go on an Arndale (running 3.14-rc6 with LPAE enabled). Everything that worked before works now too. Also, I've tested the /0 and this gave the SIGILL as expected; and putting gettimeofday in a big loop made it appear as [vdso] code in perf. So I'm happy to keep the Tested-by on this. Cheers, -- Steve