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Date:   Thu, 19 Sep 2019 21:45:23 +0300
From:   Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org>
To:     ast@kernel.org, daniel@iogearbox.net, kafai@fb.com, andriin@fb.com
Cc:     yhs@fb.com, netdev@vger.kernel.org, bpf@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH bpf] libbpf: fix version identification on busybox
Message-ID: <20190919184521.GB8870@khorivan>
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References: <20190919160518.25901-1-ivan.khoronzhuk@linaro.org>
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On Thu, Sep 19, 2019 at 07:05:18PM +0300, Ivan Khoronzhuk wrote:
>It's very often for embedded to have stripped version of sort in
>busybox, when no -V option present. It breaks build natively on target
>board causing recursive loop.
>
>BusyBox v1.24.1 (2019-04-06 04:09:16 UTC) multi-call binary. \
>Usage: sort [-nrugMcszbdfimSTokt] [-o FILE] [-k \
>start[.offset][opts][,end[.offset][opts]] [-t CHAR] [FILE]...
>
>Lets modify command a little to avoid -V option.
>
>Fixes: dadb81d0afe732 ("libbpf: make libbpf.map source of truth for libbpf version")
>
>Signed-off-by: Ivan Khoronzhuk <ivan.khoronzhuk@linaro.org>
>---
>
>Based on bpf/master
>
> tools/lib/bpf/Makefile | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
>diff --git a/tools/lib/bpf/Makefile b/tools/lib/bpf/Makefile
>index c6f94cffe06e..a12490ad6215 100644
>--- a/tools/lib/bpf/Makefile
>+++ b/tools/lib/bpf/Makefile
>@@ -3,7 +3,7 @@
>
> LIBBPF_VERSION := $(shell \
> 	grep -oE '^LIBBPF_([0-9.]+)' libbpf.map | \
>-	sort -rV | head -n1 | cut -d'_' -f2)
>+	cut -d'_' -f2 | sort -r | head -n1)
> LIBBPF_MAJOR_VERSION := $(firstword $(subst ., ,$(LIBBPF_VERSION)))

Also can be replaced a lidder harder, with:

LIBBPFMAP := $(shell cat libbpf.map)
LIBBPF_VERSIONS := $(sort $(patsubst %;,%,$(patsubst LIBBPF_%,%,$(filter LIBBPF_%, $(LIBBPFMAP)))))
LIBBPF_VERSION := $(word $(words $(LIBBPF_VERSIONS)), $(LIBBPF_VERSIONS))

You choose, I'm not sure in "sort" of make the same on all systems.

>
> MAKEFLAGS += --no-print-directory
>-- 
>2.17.1
>

-- 
Regards,
Ivan Khoronzhuk