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From: Ihor Solodrai <ihor.solodrai@linux.dev>
To: Vitaly Chikunov <vt@altlinux.org>
Cc: Alexei Starovoitov <ast@kernel.org>,
	Andrii Nakryiko <andrii@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	bpf@vger.kernel.org, kernel-team@meta.com
Subject: Re: [PATCH bpf v2] resolve_btfids: Fix linker flags detection
Date: Tue, 3 Mar 2026 12:17:43 -0800	[thread overview]
Message-ID: <609c1db8-e674-4d65-8082-43e9fa4fbc9a@linux.dev> (raw)
In-Reply-To: <aac-hefhJ8znydSb@altlinux.org>

On 3/3/26 12:06 PM, Vitaly Chikunov wrote:
> Ihor,
> 
> [...]
>>  
>>  LIBELF_FLAGS := $(shell $(HOSTPKG_CONFIG) libelf --cflags 2>/dev/null)
>> +
>> +ifneq ($(filter -static,$(EXTRA_LDFLAGS)),)
>> +LIBELF_LIBS  := $(shell $(HOSTPKG_CONFIG) libelf --libs --static 2>/dev/null || echo -lelf -lzstd)
>> +else
>>  LIBELF_LIBS  := $(shell $(HOSTPKG_CONFIG) libelf --libs 2>/dev/null || echo -lelf)
>> +endif
>>  
>>  ZLIB_LIBS  := $(shell $(HOSTPKG_CONFIG) zlib --libs 2>/dev/null || echo -lz)
> 
> Perhaps, this line is not needed either, as `pkg-config libelf --libs
> --static` will add -lz.

The -lz has been there forever too [1], and a duplicate lib flag is
harmless here.  We also want to have reasonable defaults if pkg-config
is not available.

That said, the same can be achieved with the diff pasted below.

I don't mind either way, let's see if maintainers have an opinion.

diff --git a/tools/bpf/resolve_btfids/Makefile b/tools/bpf/resolve_btfids/Makefile
index 7672208f65e4..a7dac1587344 100644
--- a/tools/bpf/resolve_btfids/Makefile
+++ b/tools/bpf/resolve_btfids/Makefile
@@ -66,13 +66,11 @@ $(BPFOBJ): $(wildcard $(LIBBPF_SRC)/*.[ch] $(LIBBPF_SRC)/Makefile) | $(LIBBPF_OU
 LIBELF_FLAGS := $(shell $(HOSTPKG_CONFIG) libelf --cflags 2>/dev/null)
 
 ifneq ($(filter -static,$(EXTRA_LDFLAGS)),)
-LIBELF_LIBS  := $(shell $(HOSTPKG_CONFIG) libelf --libs --static 2>/dev/null || echo -lelf -lzstd)
+LIBELF_LIBS  := $(shell $(HOSTPKG_CONFIG) libelf --libs --static 2>/dev/null || echo -lelf -lzstd -lz)
 else
-LIBELF_LIBS  := $(shell $(HOSTPKG_CONFIG) libelf --libs 2>/dev/null || echo -lelf)
+LIBELF_LIBS  := $(shell $(HOSTPKG_CONFIG) libelf --libs 2>/dev/null || echo -lelf -lz)
 endif
 
-ZLIB_LIBS  := $(shell $(HOSTPKG_CONFIG) zlib --libs 2>/dev/null || echo -lz)
-
 HOSTCFLAGS_resolve_btfids += -g \
           -I$(srctree)/tools/include \
           -I$(srctree)/tools/include/uapi \
@@ -81,7 +79,7 @@ HOSTCFLAGS_resolve_btfids += -g \
           $(LIBELF_FLAGS) \
           -Wall -Werror
 
-LIBS = $(LIBELF_LIBS) $(ZLIB_LIBS)
+LIBS = $(LIBELF_LIBS)
 
 export srctree OUTPUT HOSTCFLAGS_resolve_btfids Q HOSTCC HOSTLD HOSTAR
 include $(srctree)/tools/build/Makefile.include


[1] https://lore.kernel.org/bpf/20200711215329.41165-2-jolsa@kernel.org/

> 
> Thanks,
> 
>> -ZSTD_LIBS  := $(shell $(HOSTPKG_CONFIG) libzstd --libs 2>/dev/null || echo -lzstd)
>>  
>>  HOSTCFLAGS_resolve_btfids += -g \
>>            -I$(srctree)/tools/include \
>> @@ -76,7 +81,7 @@ HOSTCFLAGS_resolve_btfids += -g \
>>            $(LIBELF_FLAGS) \
>>            -Wall -Werror
>>  
>> -LIBS = $(LIBELF_LIBS) $(ZLIB_LIBS) $(ZSTD_LIBS)
>> +LIBS = $(LIBELF_LIBS) $(ZLIB_LIBS)
>>  
>>  export srctree OUTPUT HOSTCFLAGS_resolve_btfids Q HOSTCC HOSTLD HOSTAR
>>  include $(srctree)/tools/build/Makefile.include
>> -- 
>> 2.53.0


  reply	other threads:[~2026-03-03 20:17 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-03-03 19:39 [PATCH bpf v2] resolve_btfids: Fix linker flags detection Ihor Solodrai
2026-03-03 20:06 ` Vitaly Chikunov
2026-03-03 20:17   ` Ihor Solodrai [this message]
2026-03-04 19:47 ` Vitaly Chikunov

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