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Date: Sat, 21 Nov 2015 20:45:38 +0000 From: Måns Rullgård <mans@...sr.com> To: Arnd Bergmann <arnd@...db.de>, Stephen Boyd <sboyd@...eaurora.org> CC: linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org, linux-arm-msm@...r.kernel.org, Nicolas Pitre <nico@...xnic.net>, Steven Rostedt <rostedt@...dmis.org> Subject: Re: [RFC/PATCH 0/3] ARM: Use udiv/sdiv for __aeabi_{u}idiv library functions On 21 November 2015 20:39:58 GMT+00:00, Arnd Bergmann <arnd@...db.de> wrote: >On Friday 20 November 2015 17:23:14 Stephen Boyd wrote: >> This is a respin of a patch series from about a year ago[1]. I >realized >> that we already had most of the code in recordmcount to figure out >> where we make calls to particular functions, so recording where >> we make calls to the integer division functions should be easy enough >> to add support for in the same codepaths. Looking back on the thread >> it seems like Mans was thinking along the same lines, although it >wasn't >> obvious to me back then or even over the last few days when I wrote >this. > >Shouldn't we start by allowing to build the kernel for -march=armv7ve >on platforms that allow it? That would seem like a simpler change >and likely generate better code for most people, except when you >actually >care about running the same binary kernel on older platforms. > >I tried to get a complete list of CPU cores with idiv, lpae and >virtualization support at some point, but I don't remember the >details for all Qualcomm and Marvell cores any more, to create the >complete configuration matrix. IIRC, all CPUs that support >virtualization also do lpae (they have to) and all CPUs that >do lpae also do idiv, but the opposite is not true. > > Arnd The ARM ARM says anything with virt has idiv, lpae doesn't matter. ARMv7-R also has idiv. I've no idea if anyone runs Linux on those though. -- Måns Rullgård -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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