From mboxrd@z Thu Jan 1 00:00:00 1970 From: kim.phillips@freescale.com (Kim Phillips) Date: Wed, 20 Feb 2013 21:49:43 -0600 Subject: [RFC] arm: use built-in byte swap function In-Reply-To: References: <20130129181046.GC25415@pd.tnic> <20130205210436.670c62e26d2121330e87af35@freescale.com> <1360141322.6066.4.camel@shinybook.infradead.org> <20130206191905.ac8eb6743e69425f30888704@freescale.com> <20130207181315.GM17833@n2100.arm.linux.org.uk> <1360344301.6066.263.camel@shinybook.infradead.org> <1360363233.6066.283.camel@shinybook.infradead.org> <20130208191208.2ef3d78bda71aa7b44d00d7b@freescale.com> <20130219203115.114eab79e8d2099c6306d921@freescale.com> <1361356696.13482.269.camel@i7.infradead.org> <1361367842.13482.279.camel@i7.infradead.org> <1361372008.13482.280.camel@i7.infradead.org> Message-ID: <20130220214943.9b28a5b208da9f081387c55e@freescale.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Wed, 20 Feb 2013 10:43:18 -0500 Nicolas Pitre wrote: > On Wed, 20 Feb 2013, Woodhouse, David wrote: > > On Wed, 2013-02-20 at 09:06 -0500, Nicolas Pitre wrote: > > > ... in which case there is no harm shipping a .c file and trivially > > > enforcing -O2, the rest being equal. > > > > For today's compilers, unless the wind changes. > > We'll adapt if necessary. Going with -O2 should remain pretty safe anyway. Alas, not so for gcc 4.4 - I had forgotten I had tested Ubuntu/Linaro 4.4.7-1ubuntu2 here: https://patchwork.kernel.org/patch/2101491/ add -O2 to that test script and gcc 4.4 *always* emits calls to __bswap[sd]i2, even with -march=armv6k+. I'll try working on an assembly version given it probably makes more sense, future-gcc-immunity-wise. Otherwise we're back to the old 'if GCC_VERSION >= 40500' in arch/arm/include/asm/swab.h... Kim