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From: Andrii Nakryiko <andrii.nakryiko@gmail.com>
To: Andreas Schwab <schwab@linux-m68k.org>
Cc: Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org>,
	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 01/14] samples: bpf: makefile: fix HDR_PROBE "echo"
Date: Mon, 16 Sep 2019 15:01:52 -0700
Message-ID: <CAEf4BzZnv0Cy8KTYaso-G-TYj_UM6MbEYEi_d14DmW2W=VuLhg@mail.gmail.com> (raw)
In-Reply-To: <8736gvexfz.fsf@igel.home>

On Mon, Sep 16, 2019 at 2:35 PM Andreas Schwab <schwab@linux-m68k.org> wrote:
>
> On Sep 16 2019, Andrii Nakryiko <andrii.nakryiko@gmail.com> wrote:
>
> > On Mon, Sep 16, 2019 at 3:59 AM Ivan Khoronzhuk
> > <ivan.khoronzhuk@linaro.org> wrote:
> >>
> >> echo should be replaced with echo -e to handle '\n' correctly, but
> >> instead, replace it with printf as some systems can't handle echo -e.
> >>
> >> Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org>
> >> ---
> >>  samples/bpf/Makefile | 2 +-
> >>  1 file changed, 1 insertion(+), 1 deletion(-)
> >>
> >> diff --git a/samples/bpf/Makefile b/samples/bpf/Makefile
> >> index 1d9be26b4edd..f50ca852c2a8 100644
> >> --- a/samples/bpf/Makefile
> >> +++ b/samples/bpf/Makefile
> >> @@ -201,7 +201,7 @@ endif
> >>
> >>  # Don't evaluate probes and warnings if we need to run make recursively
> >>  ifneq ($(src),)
> >> -HDR_PROBE := $(shell echo "\#include <linux/types.h>\n struct list_head { int a; }; int main() { return 0; }" | \
> >> +HDR_PROBE := $(shell printf "\#include <linux/types.h>\n struct list_head { int a; }; int main() { return 0; }" | \
> >
> > printf change is fine, but I'm confused about \# at the beginning of
> > the string.
>
> From the NEWS of make 4.3:
>
> * WARNING: Backward-incompatibility!
>   Number signs (#) appearing inside a macro reference or function invocation
>   no longer introduce comments and should not be escaped with backslashes:
>   thus a call such as:
>     foo := $(shell echo '#')
>   is legal.  Previously the number sign needed to be escaped, for example:
>     foo := $(shell echo '\#')
>   Now this latter will resolve to "\#".  If you want to write makefiles
>   portable to both versions, assign the number sign to a variable:
>     H := \#
>     foo := $(shell echo '$H')
>   This was claimed to be fixed in 3.81, but wasn't, for some reason.
>   To detect this change search for 'nocomment' in the .FEATURES variable.
>
> Andreas.

Oh, subtle... Thanks for explaining!

>
> --
> Andreas Schwab, schwab@linux-m68k.org
> GPG Key fingerprint = 7578 EB47 D4E5 4D69 2510  2552 DF73 E780 A9DA AEC1
> "And now for something completely different."

  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 [this message]
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
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

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