BPF Archive on lore.kernel.org
 help / color / Atom feed
From: Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org>
To: Andrii Nakryiko <andrii.nakryiko@gmail.com>
Cc: Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Yonghong Song <yhs@fb.com>,
	"David S. Miller" <davem@davemloft.net>,
	Jakub Kicinski <jakub.kicinski@netronome.com>,
	Jesper Dangaard Brouer <hawk@kernel.org>,
	john fastabend <john.fastabend@gmail.com>,
	open list <linux-kernel@vger.kernel.org>,
	Networking <netdev@vger.kernel.org>, bpf <bpf@vger.kernel.org>,
	clang-built-linux@googlegroups.com,
	sergei.shtylyov@cogentembedded.com
Subject: Re: [PATCH v3 bpf-next 11/14] libbpf: makefile: add C/CXX/LDFLAGS to libbpf.so and test_libpf targets
Date: Wed, 18 Sep 2019 14:05:18 +0300
Message-ID: <20190918110517.GD2908@khorivan> (raw)
In-Reply-To: <CAEf4BzZXNN_dhs=jUjtfCqtuV1bk9H=q5b07kVDQQsysjhF4cQ@mail.gmail.com>

On Tue, Sep 17, 2019 at 10:19:22PM -0700, Andrii Nakryiko wrote:
>On Mon, Sep 16, 2019 at 4:00 AM Ivan Khoronzhuk
><ivan.khoronzhuk@linaro.org> wrote:
>>
>> In case of LDFLAGS and EXTRA_CC/CXX flags there is no way to pass them
>> correctly to build command, for instance when --sysroot is used or
>> external libraries are used, like -lelf, wich can be absent in
>> toolchain. This can be used for samples/bpf cross-compiling allowing
>> to get elf lib from sysroot.
>>
>> Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org>
>> ---
>>  tools/lib/bpf/Makefile | 11 ++++++++---
>>  1 file changed, 8 insertions(+), 3 deletions(-)
>>
>> diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
>> index c6f94cffe06e..bccfa556ef4e 100644
>> --- a/tools/lib/bpf/Makefile
>> +++ b/tools/lib/bpf/Makefile
>> @@ -94,6 +94,10 @@ else
>>    CFLAGS := -g -Wall
>>  endif
>>
>> +ifdef EXTRA_CXXFLAGS
>> +  CXXFLAGS := $(EXTRA_CXXFLAGS)
>> +endif
>> +
>>  ifeq ($(feature-libelf-mmap), 1)
>>    override CFLAGS += -DHAVE_LIBELF_MMAP_SUPPORT
>>  endif
>> @@ -176,8 +180,9 @@ $(BPF_IN): force elfdep bpfdep
>>  $(OUTPUT)libbpf.so: $(OUTPUT)libbpf.so.$(LIBBPF_VERSION)
>>
>>  $(OUTPUT)libbpf.so.$(LIBBPF_VERSION): $(BPF_IN)
>> -       $(QUIET_LINK)$(CC) --shared -Wl,-soname,libbpf.so.$(LIBBPF_MAJOR_VERSION) \
>> -                                   -Wl,--version-script=$(VERSION_SCRIPT) $^ -lelf -o $@
>> +       $(QUIET_LINK)$(CC) $(LDFLAGS) \
>> +               --shared -Wl,-soname,libbpf.so.$(LIBBPF_MAJOR_VERSION) \
>> +               -Wl,--version-script=$(VERSION_SCRIPT) $^ -lelf -o $@
>>         @ln -sf $(@F) $(OUTPUT)libbpf.so
>>         @ln -sf $(@F) $(OUTPUT)libbpf.so.$(LIBBPF_MAJOR_VERSION)
>>
>> @@ -185,7 +190,7 @@ $(OUTPUT)libbpf.a: $(BPF_IN)
>>         $(QUIET_LINK)$(RM) $@; $(AR) rcs $@ $^
>>
>>  $(OUTPUT)test_libbpf: test_libbpf.cpp $(OUTPUT)libbpf.a
>> -       $(QUIET_LINK)$(CXX) $(INCLUDES) $^ -lelf -o $@
>> +       $(QUIET_LINK)$(CXX) $(CXXFLAGS) $(LDFLAGS) $(INCLUDES) $^ -lelf -o $@
>
>Instead of doing ifdef EXTRA_CXXFLAGS bit above, you can just include
>both $(CXXFLAGS) and $(EXTRA_CXXFLAGS), which will do the right thing
>(and is actually recommended my make documentation way to do this).
It's good practice to follow existent style, I've done similar way as for
CFLAGS + EXTRACFLAGS here, didn't want to verify it can impact on
smth else. And my goal is not to correct everything but embed my
functionality, series tool large w/o it.

>
>But actually, there is no need to use C++ compiler here,
>test_libbpf.cpp can just be plain C. Do you mind renaming it to .c and
>using C compiler instead?
Seems like, will try in next v.

>
>>
>>  $(OUTPUT)libbpf.pc:
>>         $(QUIET_GEN)sed -e "s|@PREFIX@|$(prefix)|" \
>> --
>> 2.17.1
>>

-- 
Regards,
Ivan Khoronzhuk

  reply index

Thread overview: 45+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-16 10:54 [PATCH v3 bpf-next 00/14] samples: bpf: improve/fix cross-compilation Ivan Khoronzhuk
2019-09-16 10:54 ` [PATCH v3 bpf-next 01/14] samples: bpf: makefile: fix HDR_PROBE "echo" Ivan Khoronzhuk
2019-09-16 20:13   ` Andrii Nakryiko
2019-09-16 21:22     ` Ivan Khoronzhuk
2019-09-16 21:35     ` Andreas Schwab
2019-09-16 22:01       ` Andrii Nakryiko
2019-09-16 10:54 ` [PATCH v3 bpf-next 02/14] samples: bpf: makefile: fix cookie_uid_helper_example obj build Ivan Khoronzhuk
2019-09-16 20:18   ` Andrii Nakryiko
2019-09-16 10:54 ` [PATCH v3 bpf-next 03/14] samples: bpf: makefile: use --target from cross-compile Ivan Khoronzhuk
2019-09-16 20:25   ` Andrii Nakryiko
2019-09-16 10:54 ` [PATCH v3 bpf-next 04/14] samples: bpf: use own EXTRA_CFLAGS for clang commands Ivan Khoronzhuk
2019-09-16 20:35   ` Andrii Nakryiko
2019-09-16 22:01     ` Ivan Khoronzhuk
2019-09-16 10:54 ` [PATCH v3 bpf-next 05/14] samples: bpf: makefile: use __LINUX_ARM_ARCH__ selector for arm Ivan Khoronzhuk
2019-09-16 20:44   ` Andrii Nakryiko
2019-09-16 22:04     ` Ivan Khoronzhuk
2019-09-16 10:54 ` [PATCH v3 bpf-next 06/14] samples: bpf: makefile: drop unnecessarily inclusion for bpf_load Ivan Khoronzhuk
2019-09-16 20:52   ` Andrii Nakryiko
2019-09-16 10:54 ` [PATCH v3 bpf-next 07/14] samples: bpf: add makefile.target for separate CC target build Ivan Khoronzhuk
2019-09-17 23:19   ` Andrii Nakryiko
2019-09-18 10:12     ` Ivan Khoronzhuk
2019-09-18 21:22       ` Andrii Nakryiko
2019-09-16 10:54 ` [PATCH v3 bpf-next 08/14] samples: bpf: makefile: base target programs rules on Makefile.target Ivan Khoronzhuk
2019-09-17 23:28   ` Andrii Nakryiko
2019-09-18 10:23     ` Ivan Khoronzhuk
2019-09-16 10:54 ` [PATCH v3 bpf-next 09/14] samples: bpf: makefile: use own flags but not host when cross compile Ivan Khoronzhuk
2019-09-17 10:14   ` Sergei Shtylyov
2019-09-17 23:42   ` Andrii Nakryiko
2019-09-18 10:35     ` Ivan Khoronzhuk
2019-09-18 21:29       ` Andrii Nakryiko
2019-09-19 14:18         ` Ivan Khoronzhuk
2019-09-19 17:54           ` Andrii Nakryiko
2019-09-16 10:54 ` [PATCH v3 bpf-next 10/14] samples: bpf: makefile: use target CC environment for HDR_PROBE Ivan Khoronzhuk
2019-09-18  4:20   ` Andrii Nakryiko
2019-09-16 10:54 ` [PATCH v3 bpf-next 11/14] libbpf: makefile: add C/CXX/LDFLAGS to libbpf.so and test_libpf targets Ivan Khoronzhuk
2019-09-18  5:19   ` Andrii Nakryiko
2019-09-18 11:05     ` Ivan Khoronzhuk [this message]
2019-09-18 21:42       ` Andrii Nakryiko
2019-09-16 10:54 ` [PATCH v3 bpf-next 12/14] samples: bpf: makefile: provide C/CXX/LD flags to libbpf Ivan Khoronzhuk
2019-09-18  5:20   ` Andrii Nakryiko
2019-09-16 10:54 ` [PATCH v3 bpf-next 13/14] samples: bpf: makefile: add sysroot support Ivan Khoronzhuk
2019-09-18  5:23   ` Andrii Nakryiko
2019-09-18 11:09     ` Ivan Khoronzhuk
2019-09-16 10:54 ` [PATCH v3 bpf-next 14/14] samples: bpf: README: add preparation steps and sysroot info Ivan Khoronzhuk
2019-09-18  5:33 ` [PATCH v3 bpf-next 00/14] samples: bpf: improve/fix cross-compilation Andrii Nakryiko

Reply instructions:

You may reply publically to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20190918110517.GD2908@khorivan \
    --to=ivan.khoronzhuk@linaro.org \
    --cc=andrii.nakryiko@gmail.com \
    --cc=ast@kernel.org \
    --cc=bpf@vger.kernel.org \
    --cc=clang-built-linux@googlegroups.com \
    --cc=daniel@iogearbox.net \
    --cc=davem@davemloft.net \
    --cc=hawk@kernel.org \
    --cc=jakub.kicinski@netronome.com \
    --cc=john.fastabend@gmail.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=netdev@vger.kernel.org \
    --cc=sergei.shtylyov@cogentembedded.com \
    --cc=yhs@fb.com \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

BPF Archive on lore.kernel.org

Archives are clonable:
	git clone --mirror https://lore.kernel.org/bpf/0 bpf/git/0.git

	# If you have public-inbox 1.1+ installed, you may
	# initialize and index your mirror using the following commands:
	public-inbox-init -V2 bpf bpf/ https://lore.kernel.org/bpf \
		bpf@vger.kernel.org
	public-inbox-index bpf

Example config snippet for mirrors

Newsgroup available over NNTP:
	nntp://nntp.lore.kernel.org/org.kernel.vger.bpf


AGPL code for this site: git clone https://public-inbox.org/public-inbox.git