lkml.org 
[lkml]   [2022]   [Jul]   [12]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH bpf-next 1/3] samples: bpf: Fix cross-compiling error by using bootstrap bpftool
From
On 12/07/2022 04:08, Pu Lehui wrote:
> Currently, when cross compiling bpf samples, the host side cannot
> use arch-specific bpftool to generate vmlinux.h or skeleton. Since
> samples/bpf use bpftool for vmlinux.h, skeleton, and static linking
> only, we can use lightweight bootstrap version of bpftool to handle
> these, and it's always host-native.
>
> Signed-off-by: Pu Lehui <pulehui@huawei.com>
> Suggested-by: Andrii Nakryiko <andrii@kernel.org>
> ---
> samples/bpf/Makefile | 16 +++++++++++-----
> 1 file changed, 11 insertions(+), 5 deletions(-)
>
> diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
> index 5002a5b9a7da..57012b8259d2 100644
> --- a/samples/bpf/Makefile
> +++ b/samples/bpf/Makefile
> @@ -282,12 +282,18 @@ $(LIBBPF): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(LIBBPF_OU
>
> BPFTOOLDIR := $(TOOLS_PATH)/bpf/bpftool
> BPFTOOL_OUTPUT := $(abspath $(BPF_SAMPLES_PATH))/bpftool
> -BPFTOOL := $(BPFTOOL_OUTPUT)/bpftool
> +BPFTOOL := $(BPFTOOL_OUTPUT)/bootstrap/bpftool
> +ifeq ($(CROSS_COMPILE),)
> $(BPFTOOL): $(LIBBPF) $(wildcard $(BPFTOOLDIR)/*.[ch] $(BPFTOOLDIR)/Makefile) | $(BPFTOOL_OUTPUT)
> - $(MAKE) -C $(BPFTOOLDIR) srctree=$(BPF_SAMPLES_PATH)/../../ \
> - OUTPUT=$(BPFTOOL_OUTPUT)/ \
> - LIBBPF_OUTPUT=$(LIBBPF_OUTPUT)/ \
> - LIBBPF_DESTDIR=$(LIBBPF_DESTDIR)/
> + $(MAKE) -C $(BPFTOOLDIR) srctree=$(BPF_SAMPLES_PATH)/../../ \
> + OUTPUT=$(BPFTOOL_OUTPUT)/ \
> + LIBBPF_BOOTSTRAP_OUTPUT=$(LIBBPF_OUTPUT)/ \
> + LIBBPF_BOOTSTRAP_DESTDIR=$(LIBBPF_DESTDIR)/ bootstrap
> +else
> +$(BPFTOOL): $(wildcard $(BPFTOOLDIR)/*.[ch] $(BPFTOOLDIR)/Makefile) | $(BPFTOOL_OUTPUT)

Thanks for this! Just trying to fully understand the details here. When
cross-compiling, you leave aside the dependency on target-arch-libbpf,
so that "make -C <bpftool-dir> bootstrap" rebuilds its own host-arch
libbpf, is this correct?

> + $(MAKE) -C $(BPFTOOLDIR) srctree=$(BPF_SAMPLES_PATH)/../../ \
> + OUTPUT=$(BPFTOOL_OUTPUT)/ bootstrap
> +endif
>
> $(LIBBPF_OUTPUT) $(BPFTOOL_OUTPUT):
> $(call msg,MKDIR,$@)

\
 
 \ /
  Last update: 2022-07-12 12:13    [W:0.066 / U:1.008 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site