diff options
| author | Tom Rini <trini@konsulko.com> | 2018-04-22 19:15:03 -0400 |
|---|---|---|
| committer | Tom Rini <trini@konsulko.com> | 2018-04-27 14:54:49 -0400 |
| commit | 3b6407b8ed95594de6ee4fddd3239e8841b4d2d6 (patch) | |
| tree | 1d63fdae996ec5b9b230e65674a086de3794a10d /doc/README.clang | |
| parent | 4760fe26c72563d284cd620421dc8196006ce5e3 (diff) | |
clang: Update documentation
As of clang-5.0, things have changed a bit. First, we cannot
automatically guess -target values as if we do not pass one with CC then
cc-option will fail. Second, to disable movt/movw relocations the
argument has become -mno-movt.
Related to the target part, we cannot use arm-none-eabi as that ends up
being too generic of an ARM target for things like say rpi_3_32b to
work.
Signed-off-by: Tom Rini <trini@konsulko.com>
Diffstat (limited to 'doc/README.clang')
| -rw-r--r-- | doc/README.clang | 18 |
1 files changed, 7 insertions, 11 deletions
diff --git a/doc/README.clang b/doc/README.clang index e0491b2d7e..475bb1e2ed 100644 --- a/doc/README.clang +++ b/doc/README.clang @@ -10,16 +10,11 @@ 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: Most notably boards which aren't using -the generic board will fail to compile, but since those are expected -to be converted this will solve itself. 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. - -NOTE: without the -mllvm -arm-use-movt=0 flags U-Boot will compile -fine, but llvm might hardcode addresses in movw / movt pairs, which -cannot be relocated and U-Boot will fail at runtime. +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) -------------- @@ -29,7 +24,8 @@ 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 -j8 +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 |