Re: [PATCH v2 4/4] perf augmented_raw_syscalls: Document clang configuration

From: Arnaldo Carvalho de Melo
Date: Thu Jun 06 2019 - 10:12:13 EST


Em Thu, Jun 06, 2019 at 05:48:45PM +0800, Leo Yan escreveu:
> To build this program successfully with clang, there have three
> compiler options need to be specified:
>
> - Header file path: tools/perf/include/bpf;
> - Specify architecture;
> - Define macro __NR_CPUS__.

So, this shouldn't be needed, all of this is supposed to be done
automagically, have you done a 'make -C tools/perf install'?

- Arnaldo

> This patch add comments to explain the reasons for building failure and
> give two examples for llvm.clang-opt variable, one is for x86_64
> architecture and another is for aarch64 architecture.
>
> Signed-off-by: Leo Yan <leo.yan@xxxxxxxxxx>
> ---
> .../examples/bpf/augmented_raw_syscalls.c | 19 +++++++++++++++++++
> 1 file changed, 19 insertions(+)
>
> diff --git a/tools/perf/examples/bpf/augmented_raw_syscalls.c b/tools/perf/examples/bpf/augmented_raw_syscalls.c
> index a3701a4daf2e..fb6987edab2c 100644
> --- a/tools/perf/examples/bpf/augmented_raw_syscalls.c
> +++ b/tools/perf/examples/bpf/augmented_raw_syscalls.c
> @@ -6,6 +6,25 @@
> *
> * perf trace -e tools/perf/examples/bpf/augmented_raw_syscalls.c cat /etc/passwd > /dev/null
> *
> + * This program include two header files 'unistd.h' and 'pid_filter.h', which
> + * are placed in the folder tools/perf/include/bpf, but this folder is not
> + * included in env $KERNEL_INC_OPTIONS and it leads to compilation failure.
> + * For building this code, we also need to specify architecture and define macro
> + * __NR_CPUS__. To resolve these issues, variable llvm.clang-opt can be set in
> + * the file ~/.perfconfig:
> + *
> + * E.g. Test on a platform with 8 CPUs with x86_64 architecture:
> + *
> + * [llvm]
> + * clang-opt = "-D__NR_CPUS__=8 -D__x86_64__ \
> + * -I./tools/perf/include/bpf"
> + *
> + * E.g. Test on a platform with 5 CPUs with aarch64 architecture:
> + *
> + * [llvm]
> + * clang-opt = "-D__NR_CPUS__=5 -D__aarch64__ \
> + * -I./tools/perf/include/bpf"
> +
> * This exactly matches what is marshalled into the raw_syscall:sys_enter
> * payload expected by the 'perf trace' beautifiers.
> *
> --
> 2.17.1

--

- Arnaldo