colibri_imx6: fix video stdout in default environment

[oweals/u-boot.git] / doc / README.clang

diff --git a/doc/README.clang b/doc/README.clang
index 52495d311677f79e5961acfa42aa8e7cd30f6a39..475bb1e2ed8b442178ca2615603974473373b5f5 100644 (file)
--- a/doc/README.clang
+++ b/doc/README.clang
@@ -1,4 +1,4 @@
-The biggest problem when trying to compile U-boot with clang is that
+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
@@ -10,26 +10,26 @@ 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)
 --------------
 Binary packages can be installed as usual, e.g.:
 sudo apt-get install clang
 
-To compile U-Boot with clang on linux without IAS use e.g.:
-export TRIPLET=arm-linux-gnueabi && export CROSS_COMPILE="$TRIPLET-"
-make HOSTCC=clang CC="clang -target $TRIPLET -mllvm -arm-use-movt=0 -no-integrated-as" rpi_b_defconfig
-make HOSTCC=clang CC="clang -target $TRIPLET -mllvm -arm-use-movt=0 -no-integrated-as" all V=1 -j8
+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):
 --------------------
@@ -42,15 +42,14 @@ 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 CC="clang -target arm-freebsd-eabi --sysroot /usr/arm-freebsd -no-integrated-as -mllvm -arm-use-movt=0" rpi_b_defconfig
-gmake CC="clang -target arm-freebsd-eabi --sysroot /usr/arm-freebsd -no-integrated-as -mllvm -arm-use-movt=0" -j8
+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
+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 -no-integrated-as -mllvm -arm-use-movt=0 "$@"
-
+exec clang -target arm-freebsd-eabi --sysroot /usr/arm-freebsd "$@"