From d27087c76e3c859ea05b7581ef7ce8aa5a088dd8 Mon Sep 17 00:00:00 2001 From: Leo Yan Date: Wed, 17 Jul 2024 09:22:11 +0100 Subject: [PATCH] perf docs: Document cross compilation Records the commands for cross compilation with two methods. The first method relies on Multiarch. The second approach is to explicitly specify the PKG_CONFIG variables, which is widely used in build system (like Buildroot, Yocto, etc). Co-developed-by: James Clark Signed-off-by: James Clark Signed-off-by: Leo Yan Tested-by: Ian Rogers Cc: amadio@gentoo.org Cc: Thomas Richter Link: https://lore.kernel.org/r/20240717082211.524826-7-leo.yan@arm.com Signed-off-by: Namhyung Kim --- tools/perf/Documentation/Build.txt | 28 ++++++++++++++++++++++++++++ 1 file changed, 28 insertions(+) diff --git a/tools/perf/Documentation/Build.txt b/tools/perf/Documentation/Build.txt index 3766886c4bca..83dc87c662b6 100644 --- a/tools/perf/Documentation/Build.txt +++ b/tools/perf/Documentation/Build.txt @@ -71,3 +71,31 @@ supported by GCC. UBSan detects undefined behaviors of programs at runtime. $ UBSAN_OPTIONS=print_stacktrace=1 ./perf record -a If UBSan detects any problem at runtime, it outputs a “runtime error:” message. + +4) Cross compilation +==================== +As Multiarch is commonly supported in Linux distributions, we can install +libraries for multiple architectures on the same system and then cross-compile +Linux perf. For example, Aarch64 libraries and toolchains can be installed on +an x86_64 machine, allowing us to compile perf for an Aarch64 target. + +Below is the command for building the perf with dynamic linking. + + $ cd /path/to/Linux + $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- -C tools/perf + +For static linking, the option `LDFLAGS="-static"` is required. + + $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- \ + LDFLAGS="-static" -C tools/perf + +In the embedded system world, a use case is to explicitly specify the package +configuration paths for cross building: + + $ PKG_CONFIG_SYSROOT_DIR="/path/to/cross/build/sysroot" \ + PKG_CONFIG_LIBDIR="/usr/lib/:/usr/local/lib" \ + make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- -C tools/perf + +In this case, the variable PKG_CONFIG_SYSROOT_DIR can be used alongside the +variable PKG_CONFIG_LIBDIR or PKG_CONFIG_PATH to prepend the sysroot path to +the library paths for cross compilation.