On Sat, Feb 22, 2020 at 11:07:14AM +0900, Masahiro Yamada wrote: > On Sat, Feb 22, 2020 at 9:40 AM Alex Xu (Hello71) <alex_y_xu@xxxxxxxx> wrote: > > > > -pipe reduces unnecessary disk wear for systems where /tmp is not a > > tmpfs, slightly increases compilation speed, and avoids leaving behind > > files when gcc crashes. > > > > According to the gcc manual, "this fails to work on some systems where > > the assembler is unable to read from a pipe; but the GNU assembler has > > no trouble". We already require GNU ld on all platforms, so this is not > > an additional dependency. LLVM as also supports pipes. > > > > -pipe has always been used for most architectures, this change > > standardizes it globally. Most notably, arm, arm64, riscv, and x86 are > > affected. > > > > Signed-off-by: Alex Xu (Hello71) <alex_y_xu@xxxxxxxx> > > <snip> > > > diff --git a/arch/arc/Makefile b/arch/arc/Makefile > > index 20e9ab6cc521..b6a2f553771c 100644 > > --- a/arch/arc/Makefile > > +++ b/arch/arc/Makefile > > @@ -9,7 +9,7 @@ ifeq ($(CROSS_COMPILE),) > > CROSS_COMPILE := $(call cc-cross-prefix, arc-linux- arceb-linux-) > > endif > > > > -cflags-y += -fno-common -pipe -fno-builtin -mmedium-calls -D__linux__ > > +cflags-y += -fno-common -fno-builtin -mmedium-calls -D__linux__ > > cflags-$(CONFIG_ISA_ARCOMPACT) += -mA7 > > cflags-$(CONFIG_ISA_ARCV2) += -mcpu=hs38 > > > > diff --git a/arch/arm/Makefile b/arch/arm/Makefile > > index db857d07114f..7711467e0797 100644 > > --- a/arch/arm/Makefile > > +++ b/arch/arm/Makefile > > @@ -21,7 +21,6 @@ KBUILD_LDS_MODULE += $(srctree)/arch/arm/kernel/module.lds > > endif > > > > GZFLAGS :=-9 > > -#KBUILD_CFLAGS +=-pipe > > > This was commented out by a very old commit, > which is available in the historical git tree. > > https://git.kernel.org/pub/scm/linux/kernel/git/history/history.git/commit/?id=ce20ed858a20f6f04de475cae79e40d3697f4776 > > But, I could not parse the reason from the commit message. > Russell, do you remember why? -pipe may reduce the disk load but increases the CPU load, so it's an option that's up to the build environment. One may wish to pass a lower parralellism when using -pipe to make to mitigate that, but both options are up to the build environment to decide upon. If we unconditionally add -pipe, then we take away choice. -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTC broadband for 0.8mile line in suburbia: sync at 12.1Mbps down 622kbps up According to speedtest.net: 11.9Mbps down 500kbps up
