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

From: Arnaldo Carvalho de Melo <[email-masked]>
Date: Thu, 6 Jun 2019 11:08:00 -0300

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 <[email-masked]>
> ---
>  .../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