On 2022/7/8 10:46, Pu Lehui wrote:
On 2022/7/8 3:12, Song Liu wrote:
On Jul 7, 2022, at 7:08 AM, Pu Lehui <pulehui@xxxxxxxxxx> wrote:
Currently, when cross compiling bpf samples, the host side
cannot use arch-specific bpftool to generate vmlinux.h or
skeleton. We need to compile the bpftool with the host
compiler.
Signed-off-by: Pu Lehui <pulehui@xxxxxxxxxx>
---
samples/bpf/Makefile | 8 ++++----
1 file changed, 4 insertions(+), 4 deletions(-)
diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
index 5002a5b9a7da..fe54a8c8f312 100644
--- a/samples/bpf/Makefile
+++ b/samples/bpf/Makefile
@@ -1,4 +1,5 @@
# SPDX-License-Identifier: GPL-2.0
+-include tools/scripts/Makefile.include
Why do we need the -include here?
HOSTLD is defined in tools/scripts/Makefile.include, we need to add it.
And for -include, mainly to resolve some conflicts:
1. If workdir is kernel_src, then 'include
tools/scripts/Makefile.include' is fine when 'make M=samples/bpf'.
2. Since the trick in samples/bpf/Makefile:
# Trick to allow make to be run from this directory
all:
$(MAKE) -C ../../ M=$(CURDIR) BPF_SAMPLES_PATH=$(CURDIR)
If workdir is samples/bpf, the compile process will first load the
Makefile in samples/bpf, then change workdir to kernel_src and load the
kernel_src's Makefile. So if we just add 'include
tools/scripts/Makefile.include', then the first load will occur error
for not found the file, so we add -include to skip the first load.
sorry, correct the reply, so we add -include to skip the
'tools/scripts/Makefile.include' file on the fisrt load.
Thanks,
Song
BPF_SAMPLES_PATH ?= $(abspath $(srctree)/$(src))
TOOLS_PATH := $(BPF_SAMPLES_PATH)/../../tools
@@ -283,11 +284,10 @@ $(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): $(LIBBPF) $(wildcard $(BPFTOOLDIR)/*.[ch]
$(BPFTOOLDIR)/Makefile) | $(BPFTOOL_OUTPUT)
+$(BPFTOOL): $(wildcard $(BPFTOOLDIR)/*.[ch] $(BPFTOOLDIR)/Makefile)
| $(BPFTOOL_OUTPUT)
$(MAKE) -C $(BPFTOOLDIR) srctree=$(BPF_SAMPLES_PATH)/../../ \
- OUTPUT=$(BPFTOOL_OUTPUT)/ \
- LIBBPF_OUTPUT=$(LIBBPF_OUTPUT)/ \
- LIBBPF_DESTDIR=$(LIBBPF_DESTDIR)/
+ ARCH= CROSS_COMPILE= CC=$(HOSTCC) LD=$(HOSTLD) \
+ OUTPUT=$(BPFTOOL_OUTPUT)/
$(LIBBPF_OUTPUT) $(BPFTOOL_OUTPUT):
$(call msg,MKDIR,$@)
--
2.25.1
.
.
