[OpenWrt-Devel] Problem building modules out-of-tree (kbuild) for x86

Sun Dec 18 18:41:17 EST 2016

Hi.

I’m trying to add the Intel e1000e, igb, and ixgbe drivers that are on Source Forge.

A snapshot of my work is here:

https://github.com/pprindeville/packages/tree/sf-ether

When I build this as “make -j1 V=s” using a mostly unmodified x86_64 generic configuration, I get:

make[3]: Entering directory `/home/philip/bertram/bmu-philip.sanity/openwrt/feeds/packages/kernel/e1000e'
. /home/philip/bertram/bmu-philip.sanity/openwrt/include/shell.sh; gzip -dc /home/philip/bertram/bmu-philip.sanity/openwrt/dl/e1000e-3.3.5.3.tar.gz | tar -C /home/philip/bertram/bmu-philip.sanity/openwrt/build_dir/target-x86_64_musl-1.1.15_powercode-bmu/linux-x86_64/e1000e-3.3.5.3/.. -xf - 
touch /home/philip/bertram/bmu-philip.sanity/openwrt/build_dir/target-x86_64_musl-1.1.15_powercode-bmu/linux-x86_64/e1000e-3.3.5.3/.prepared_b318088b5b0515ca987313e94558d492
rm -f /home/philip/bertram/bmu-philip.sanity/openwrt/staging_dir/target-x86_64_musl-1.1.15_powercode-bmu/stamp/.e1000e_installed
(cd /home/philip/bertram/bmu-philip.sanity/openwrt/build_dir/target-x86_64_musl-1.1.15_powercode-bmu/linux-x86_64/e1000e-3.3.5.3/./; if [ -x ./configure ]; then find /home/philip/bertram/bmu-philip.sanity/openwrt/build_dir/target-x86_64_musl-1.1.15_powercode-bmu/linux-x86_64/e1000e-3.3.5.3/ -name config.guess | xargs -r chmod u+w; find /home/philip/bertram/bmu-philip.sanity/openwrt/build_dir/target-x86_64_musl-1.1.15_powercode-bmu/linux-x86_64/e1000e-3.3.5.3/ -name config.guess | xargs -r -n1 cp --remove-destination /home/philip/bertram/bmu-philip.sanity/openwrt/scripts/config.guess; find /home/philip/bertram/bmu-philip.sanity/openwrt/build_dir/target-x86_64_musl-1.1.15_powercode-bmu/linux-x86_64/e1000e-3.3.5.3/ -name config.sub | xargs -r chmod u+w; find /home/philip/bertram/bmu-philip.sanity/openwrt/build_dir/target-x86_64_musl-1.1.15_powercode-bmu/linux-x86_64/e1000e-3.3.5.3/ -name config.sub | xargs -r -n1 cp --remove-destination /home/philip/bertram/bmu-philip.sanity/openwrt/scripts/config.sub; AR="x86_64-openwrt-linux-musl-gcc-ar" AS="x86_64-openwrt-linux-musl-gcc -c -Os -pipe -fno-caller-saves -fno-plt -fhonour-copts -Wno-error=unused-but-set-variable -Wno-error=unused-result -iremap /home/philip/bertram/bmu-philip.sanity/openwrt/build_dir/target-x86_64_musl-1.1.15_powercode-bmu/linux-x86_64/e1000e-3.3.5.3:e1000e-3.3.5.3 -fstack-protector -D_FORTIFY_SOURCE=1 -Wl,-z,now -Wl,-z,relro" LD=x86_64-openwrt-linux-musl-ld NM="x86_64-openwrt-linux-musl-gcc-nm" CC="x86_64-openwrt-linux-musl-gcc" GCC="x86_64-openwrt-linux-musl-gcc" CXX="x86_64-openwrt-linux-musl-g++" RANLIB="x86_64-openwrt-linux-musl-gcc-ranlib" STRIP=x86_64-openwrt-linux-musl-strip OBJCOPY=x86_64-openwrt-linux-musl-objcopy OBJDUMP=x86_64-openwrt-linux-musl-objdump SIZE=x86_64-openwrt-linux-musl-size CFLAGS="-Os -pipe -fno-caller-saves -fno-plt -fhonour-copts -Wno-error=unused-but-set-variable -Wno-error=unused-result -iremap /home/philip/bertram/bmu-philip.sanity/openwrt/build_dir/target-x86_64_musl-1.1.15_powercode-bmu/linux-x86_64/e1000e-3.3.5.3:e1000e-3.3.5.3 -fstack-protector -D_FORTIFY_SOURCE=1 -Wl,-z,now -Wl,-z,relro " CXXFLAGS="-Os -pipe -fno-caller-saves -fno-plt -fhonour-copts -Wno-error=unused-but-set-variable -Wno-error=unused-result -iremap /home/philip/bertram/bmu-philip.sanity/openwrt/build_dir/target-x86_64_musl-1.1.15_powercode-bmu/linux-x86_64/e1000e-3.3.5.3:e1000e-3.3.5.3 -fstack-protector -D_FORTIFY_SOURCE=1 -Wl,-z,now -Wl,-z,relro " CPPFLAGS="-I/home/philip/bertram/bmu-philip.sanity/openwrt/staging_dir/target-x86_64_musl-1.1.15_powercode-bmu/usr/include -I/home/philip/bertram/bmu-philip.sanity/openwrt/staging_dir/target-x86_64_musl-1.1.15_powercode-bmu/include -I/home/philip/bertram/bmu-philip.sanity/openwrt/staging_dir/toolchain-x86_64_gcc-5.3.0_musl-1.1.15/usr/include -I/home/philip/bertram/bmu-philip.sanity/openwrt/staging_dir/toolchain-x86_64_gcc-5.3.0_musl-1.1.15/include/fortify -I/home/philip/bertram/bmu-philip.sanity/openwrt/staging_dir/toolchain-x86_64_gcc-5.3.0_musl-1.1.15/include " LDFLAGS="-L/home/philip/bertram/bmu-philip.sanity/openwrt/staging_dir/target-x86_64_musl-1.1.15_powercode-bmu/usr/lib -L/home/philip/bertram/bmu-philip.sanity/openwrt/staging_dir/target-x86_64_musl-1.1.15_powercode-bmu/lib -L/home/philip/bertram/bmu-philip.sanity/openwrt/staging_dir/toolchain-x86_64_gcc-5.3.0_musl-1.1.15/usr/lib -L/home/philip/bertram/bmu-philip.sanity/openwrt/staging_dir/toolchain-x86_64_gcc-5.3.0_musl-1.1.15/lib -znow -zrelro "   ./configure --target=x86_64-openwrt-linux --host=x86_64-openwrt-linux --build=x86_64-linux-gnu --program-prefix="" --program-suffix="" --prefix=/usr --exec-prefix=/usr --bindir=/usr/bin --sbindir=/usr/sbin --libexecdir=/usr/lib --sysconfdir=/etc --datadir=/usr/share --localstatedir=/var --mandir=/usr/man --infodir=/usr/info --disable-nls   ; fi; )
rm -f /home/philip/bertram/bmu-philip.sanity/openwrt/build_dir/target-x86_64_musl-1.1.15_powercode-bmu/linux-x86_64/e1000e-3.3.5.3/.configured_*
touch /home/philip/bertram/bmu-philip.sanity/openwrt/build_dir/target-x86_64_musl-1.1.15_powercode-bmu/linux-x86_64/e1000e-3.3.5.3/.configured_yyyyyyyyy
make -C "/home/philip/bertram/bmu-philip.sanity/openwrt/build_dir/target-x86_64_musl-1.1.15_powercode-bmu/linux-x86_64/linux-4.4.14" ARCH="x86" CROSS_COMPILE="x86_64-openwrt-linux-musl-" M="/home/philip/bertram/bmu-philip.sanity/openwrt/build_dir/target-x86_64_musl-1.1.15_powercode-bmu/linux-x86_64/e1000e-3.3.5.3/src" modules
make[4]: Entering directory `/home/philip/bertram/bmu-philip.sanity/openwrt/build_dir/target-x86_64_musl-1.1.15_powercode-bmu/linux-x86_64/linux-4.4.14'
  CC [M]  /home/philip/bertram/bmu-philip.sanity/openwrt/build_dir/target-x86_64_musl-1.1.15_powercode-bmu/linux-x86_64/e1000e-3.3.5.3/src/netdev.o
gcc: error: unrecognized command line option '-mskip-rax-setup'
make[5]: *** [/home/philip/bertram/bmu-philip.sanity/openwrt/build_dir/target-x86_64_musl-1.1.15_powercode-bmu/linux-x86_64/e1000e-3.3.5.3/src/netdev.o] Error 1
make[4]: *** [_module_/home/philip/bertram/bmu-philip.sanity/openwrt/build_dir/target-x86_64_musl-1.1.15_powercode-bmu/linux-x86_64/e1000e-3.3.5.3/src] Error 2
make[4]: Leaving directory `/home/philip/bertram/bmu-philip.sanity/openwrt/build_dir/target-x86_64_musl-1.1.15_powercode-bmu/linux-x86_64/linux-4.4.14'
make[3]: *** [/home/philip/bertram/bmu-philip.sanity/openwrt/build_dir/target-x86_64_musl-1.1.15_powercode-bmu/linux-x86_64/e1000e-3.3.5.3/.built] Error 2
make[3]: Leaving directory `/home/philip/bertram/bmu-philip.sanity/openwrt/feeds/packages/kernel/e1000e'
make[2]: *** [package/feeds/packages/e1000e/compile] Error 2
make[2]: Leaving directory `/home/philip/bertram/bmu-philip.sanity/openwrt'
make[1]: *** [/home/philip/bertram/bmu-philip.sanity/openwrt/staging_dir/target-x86_64_musl-1.1.15_powercode-bmu/stamp/.package_compile] Error 2
make[1]: Leaving directory `/home/philip/bertram/bmu-philip.sanity/openwrt'
make: *** [world] Error 2

but looking through the logs, I don’t see anywhere else that -mskip-rax-setup gets passed in as a compiler flag.  What am I missing?

The option is coming from build_dir/target-x86_64_musl-1.1.15_powercode-bmu/linux-x86_64/linux-4.4.14/arch/x86/Makefile:

        # Use -mskip-rax-setup if supported.
        KBUILD_CFLAGS += $(call cc-option,-mskip-rax-setup)

It seems to have been introduced with:

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/arch/x86/Makefile?id=d9ee948d82203811a545ba26b0172fce4970d1dc

and the functionality in gcc here:

------------------------------------------------------------------------
r218870 | hjl | 2014-12-18 10:35:45 -0700 (Thu, 18 Dec 2014) | 31 lines

X86-64: Add -mskip-rax-setup

The Linux kernel never passes floating point arguments around, vararg
functions or not. Hence no vector registers are ever used when calling a
vararg function.  But gcc still dutifully emits an "xor %eax,%eax" before
each and every call of a vararg function.  Since no callee use that for
anything, these instructions are redundant.

This patch adds the -mskip-rax-setup option to skip setting up RAX
register when SSE is disabled and there are no variable arguments passed
in vector registers.  Since RAX register is used to avoid unnecessarily
saving vector registers on stack when passing variable arguments, the
impacts of this option are callees may waste some stack space, misbehave
or jump to a random location.  GCC 4.4 or newer don't those issues,
regardless the RAX register value since they don't check the RAX register
value when SSE is disabled.

gcc/

        * config/i386/i386.c (ix86_expand_call): Skip setting up RAX
        register for -mskip-rax-setup when there are no parameters
        passed in vector registers.
        * config/i386/i386.opt (mskip-rax-setup): New option.
        * doc/invoke.texi: Document -mskip-rax-setup.

gcc/testsuite/

        * gcc.target/i386/amd64-abi-7.c: New tests.
        * gcc.target/i386/amd64-abi-8.c: Likwise.
        * gcc.target/i386/amd64-abi-9.c: Likwise.

————————————————————————————————————

Why would the option -mskip-rax-setup be present when doing module kbuilds out-of-tree, but not be present when building the kernel image itself or building modules in-tree?

Any help is appreciated.

Thanks,

-Philip
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