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ARM: 8801/1: makefile: use ARMv3M mode for RiscPC 

The purpose of CONFIG_CPU_32v3 is to avoid ldrh/strh on the RiscPC,
which is pretty much an ARMv4 device, except its bus will choke on the
half-words. The way to make the C compiler not output ldrh/strh is with
-march=armv3, which doesn't support them in the ISA. However, this
prevents certain cryptography code from working that uses instructions
like umull. Fortunately there's also -march=armv3m that does support
those, making it possible to continue assembling optimized cryptography
routines for our beloved RiscPC.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Russell King <rmk+kernel@armlinux.org.uk>
This commit is contained in:
Jason A. Donenfeld 2018-10-02 15:01:24 +01:00 committed by Russell King
parent f9b58e8c7d
commit 8403bcb779
1 changed files with 1 additions and 1 deletions
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arch/arm/Makefile
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@ -74,7 +74,7 @@ endif
arch-$(CONFIG_CPU_32v5) =-D__LINUX_ARM_ARCH__=5 $(call cc-option,-march=armv5te,-march=armv4t)
arch-$(CONFIG_CPU_32v4T) =-D__LINUX_ARM_ARCH__=4 -march=armv4t
arch-$(CONFIG_CPU_32v4) =-D__LINUX_ARM_ARCH__=4 -march=armv4
arch-$(CONFIG_CPU_32v3) =-D__LINUX_ARM_ARCH__=3 -march=armv3
arch-$(CONFIG_CPU_32v3) =-D__LINUX_ARM_ARCH__=3 -march=armv3m
# Evaluate arch cc-option calls now
arch-y := $(arch-y)