On Mon, Dec 21, 2015 at 01:46:22PM +0100, Ard Biesheuvel wrote: > On 21 December 2015 at 13:38, Will Deacon <will.dea...@arm.com> wrote: > > On Fri, Dec 18, 2015 at 08:17:35PM -0800, Andrew Pinski wrote: > >> The problem here is that GCC 6 and above emits .arch now > >> for each function so now the global .arch_extension has > >> no effect. This fixes the problem by putting > >> .arch_extension inside ARM64_LSE_ATOMIC_INSN so > >> it is enabled for each place where LSE is used. > > > > Hmm, this is going to affect arch/arm/ much more heavily than arch/arm64. > > .arch_extension is used for virt, mp and sec over there, and it may be > > tricky to isolate the actual instruction usage (at least, virt looks > > lost in kvm/arm.c). > > > > Why can't gas have an option to accept all instruction encodings that it > > knows about, inspite of any .arch directives? > > > > Modern GAS supports things like -march=armv7-a+mp+sec+virt, so it > probably makes sense to pass that on the command line when building > for v7 (or +sec only for v6) if the assembler is found to support it > at build time.
Modern GCCs (GCC 4 at least) add .arch / .cpu pseudo-instructions in the assembly output which means using -Wa,-march= and -Wa,-mcpu= to GCC are now totally useless. (From the bug reports I've seen, I don't deem GCC 5 to be anything but a total failure, and so as far as I'm concerned, GCC 5 is not to be used for ARM, and effectively doesn't exist. I have no experience or opinions on GCC 6. Hence, "GCC 4" still counts as "modern" being the only recent compilers that produce sane results.) -- RMK's Patch system: http://www.arm.linux.org.uk/developer/patches/ FTTC broadband for 0.8mile line: currently at 9.6Mbps down 400kbps up according to speedtest.net. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
