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Diffstat (limited to 'doc/README.clang')
| -rw-r--r-- | doc/README.clang | 55 |
1 files changed, 0 insertions, 55 deletions
diff --git a/doc/README.clang b/doc/README.clang deleted file mode 100644 index 475bb1e2ed8..00000000000 --- a/doc/README.clang +++ /dev/null @@ -1,55 +0,0 @@ -The biggest problem when trying to compile U-Boot with clang is that -almost all archs rely on storing gd in a global register and clang user -manual states: "clang does not support global register variables; this -is unlikely to be implemented soon because it requires additional LLVM -backend support." - -Since version 3.4 the ARM backend can be instructed to leave r9 alone. -Global registers themselves are not supported so some inline assembly is -used to get its value. This does lead to larger code then strictly -necessary, but at least works. - -NOTE: target compilation only work for _some_ ARM boards at the moment. -Also AArch64 is not supported currently due to a lack of private libgcc -support. Boards which reassign gd in c will also fail to compile, but there is -in no strict reason to do so in the ARM world, since crt0.S takes care of this. -These assignments can be avoided by changing the init calls but this is not in -mainline yet. - -Debian (based) --------------- -Binary packages can be installed as usual, e.g.: -sudo apt-get install clang - -Note that we still use binutils for some tools so we must continue to set -CROSS_COMPILE. To compile U-Boot with clang on linux without IAS use e.g.: -make HOSTCC=clang rpi_2_defconfig -make HOSTCC=clang CROSS_COMPILE=arm-linux-gnueabi- \ - CC="clang -target arm-linux-gnueabi" -j8 - -It can also be used to compile sandbox: -make HOSTCC=clang sandbox_defconfig -make HOSTCC=clang CC=clang -j8 - -FreeBSD 11 (Current): --------------------- -Since llvm 3.4 is currently in the base system, the integrated as is -incapable of building U-Boot. Therefore gas from devel/arm-gnueabi-binutils -is used instead. It needs a symlinks to be picked up correctly though: - -ln -s /usr/local/bin/arm-gnueabi-freebsd-as /usr/bin/arm-freebsd-eabi-as - -# The following commands compile U-Boot using the clang xdev toolchain. -# NOTE: CROSS_COMPILE and target differ on purpose! -export CROSS_COMPILE=arm-gnueabi-freebsd- -gmake rpi_2_defconfig -gmake CC="clang -target arm-freebsd-eabi --sysroot /usr/arm-freebsd" -j8 - -Given that U-Boot will default to gcc, above commands can be -simplified with a simple wrapper script, listed below. - -/usr/local/bin/arm-gnueabi-freebsd-gcc ---- -#!/bin/sh - -exec clang -target arm-freebsd-eabi --sysroot /usr/arm-freebsd "$@" |