Compilation error: error: ‘struct bpf_map_skeleton’ has no member named ‘link’ when linking against system libbpf on Fedora 41

[anh0516]

Fedora 41 just got Linux 6.12, so I decided to try scx schedulers. The C schedulers fail to build against the system libbpf, whether with static or dynamic linking. The cloned libbpf works fine.

[1/46] Generating libbpf with a custom command

[2/46] Generating bpftool_target with a custom command

[11/27] Compiling C object scheds/c/scx_central.p/scx_central.c.o
FAILED: scheds/c/scx_central.p/scx_central.c.o 
cc -Ischeds/c/scx_central.p -Ischeds/c -I../scheds/c -I../scheds/include -fdiagnostics-color=always -D_FILE_OFFSET_BITS=64 -Wall -Winvalid-pch -O3 -pthread -DWITH_GZFILEOP -MD -MQ scheds/c/scx_central.p/scx_central.c.o -MF scheds/c/scx_central.p/scx_central.c.o.d -o scheds/c/scx_central.p/scx_central.c.o -c ../scheds/c/scx_central.c
In file included from ../scheds/c/scx_central.c:16:
scheds/c/scx_central.p/scx_central.bpf.skel.h: In function ‘scx_central__create_skeleton’:
scheds/c/scx_central.p/scx_central.bpf.skel.h:354:12: error: ‘struct bpf_map_skeleton’ has no member named ‘link’
  354 |         map->link = &obj->links.central_ops;
      |            ^~
[12/27] Compiling C object scheds/c/scx_nest.p/scx_nest.c.o
FAILED: scheds/c/scx_nest.p/scx_nest.c.o 
cc -Ischeds/c/scx_nest.p -Ischeds/c -I../scheds/c -I../scheds/include -fdiagnostics-color=always -D_FILE_OFFSET_BITS=64 -Wall -Winvalid-pch -O3 -pthread -DWITH_GZFILEOP -MD -MQ scheds/c/scx_nest.p/scx_nest.c.o -MF scheds/c/scx_nest.p/scx_nest.c.o.d -o scheds/c/scx_nest.p/scx_nest.c.o -c ../scheds/c/scx_nest.c
In file included from ../scheds/c/scx_nest.c:15:
scheds/c/scx_nest.p/scx_nest.bpf.skel.h: In function ‘scx_nest__create_skeleton’:
scheds/c/scx_nest.p/scx_nest.bpf.skel.h:353:12: error: ‘struct bpf_map_skeleton’ has no member named ‘link’
  353 |         map->link = &obj->links.nest_ops;
      |            ^~
[13/27] Compiling C object scheds/c/scx_qmap.p/scx_qmap.c.o
FAILED: scheds/c/scx_qmap.p/scx_qmap.c.o 
cc -Ischeds/c/scx_qmap.p -Ischeds/c -I../scheds/c -I../scheds/include -fdiagnostics-color=always -D_FILE_OFFSET_BITS=64 -Wall -Winvalid-pch -O3 -pthread -DWITH_GZFILEOP -MD -MQ scheds/c/scx_qmap.p/scx_qmap.c.o -MF scheds/c/scx_qmap.p/scx_qmap.c.o.d -o scheds/c/scx_qmap.p/scx_qmap.c.o -c ../scheds/c/scx_qmap.c
In file included from ../scheds/c/scx_qmap.c:15:
scheds/c/scx_qmap.p/scx_qmap.bpf.skel.h: In function ‘scx_qmap__create_skeleton’:
scheds/c/scx_qmap.p/scx_qmap.bpf.skel.h:399:12: error: ‘struct bpf_map_skeleton’ has no member named ‘link’
  399 |         map->link = &obj->links.qmap_ops;
      |            ^~
[14/27] Compiling C object scheds/c/scx_simple.p/scx_simple.c.o
FAILED: scheds/c/scx_simple.p/scx_simple.c.o 
cc -Ischeds/c/scx_simple.p -Ischeds/c -I../scheds/c -I../scheds/include -fdiagnostics-color=always -D_FILE_OFFSET_BITS=64 -Wall -Winvalid-pch -O3 -pthread -DWITH_GZFILEOP -MD -MQ scheds/c/scx_simple.p/scx_simple.c.o -MF scheds/c/scx_simple.p/scx_simple.c.o.d -o scheds/c/scx_simple.p/scx_simple.c.o -c ../scheds/c/scx_simple.c
In file included from ../scheds/c/scx_simple.c:13:
scheds/c/scx_simple.p/scx_simple.bpf.skel.h: In function ‘scx_simple__create_skeleton’:
scheds/c/scx_simple.p/scx_simple.bpf.skel.h:318:12: error: ‘struct bpf_map_skeleton’ has no member named ‘link’
  318 |         map->link = &obj->links.simple_ops;
      |            ^~
[15/27] Compiling C object scheds/c/scx_userland.p/scx_userland.c.o
FAILED: scheds/c/scx_userland.p/scx_userland.c.o 
cc -Ischeds/c/scx_userland.p -Ischeds/c -I../scheds/c -I../scheds/include -fdiagnostics-color=always -D_FILE_OFFSET_BITS=64 -Wall -Winvalid-pch -O3 -pthread -DWITH_GZFILEOP -MD -MQ scheds/c/scx_userland.p/scx_userland.c.o -MF scheds/c/scx_userland.p/scx_userland.c.o.d -o scheds/c/scx_userland.p/scx_userland.c.o -c ../scheds/c/scx_userland.c
In file included from ../scheds/c/scx_userland.c:32:
scheds/c/scx_userland.p/scx_userland.bpf.skel.h: In function ‘scx_userland__create_skeleton’:
scheds/c/scx_userland.p/scx_userland.bpf.skel.h:333:12: error: ‘struct bpf_map_skeleton’ has no member named ‘link’
  333 |         map->link = &obj->links.userland_ops;
      |            ^~
[16/27] Compiling C object scheds/c/scx_flatcg.p/scx_flatcg.c.o
FAILED: scheds/c/scx_flatcg.p/scx_flatcg.c.o 
cc -Ischeds/c/scx_flatcg.p -Ischeds/c -I../scheds/c -I../scheds/include -fdiagnostics-color=always -D_FILE_OFFSET_BITS=64 -Wall -Winvalid-pch -O3 -pthread -DWITH_GZFILEOP -MD -MQ scheds/c/scx_flatcg.p/scx_flatcg.c.o -MF scheds/c/scx_flatcg.p/scx_flatcg.c.o.d -o scheds/c/scx_flatcg.p/scx_flatcg.c.o -c ../scheds/c/scx_flatcg.c
In file included from ../scheds/c/scx_flatcg.c:18:
scheds/c/scx_flatcg.p/scx_flatcg.bpf.skel.h: In function ‘scx_flatcg__create_skeleton’:
scheds/c/scx_flatcg.p/scx_flatcg.bpf.skel.h:360:12: error: ‘struct bpf_map_skeleton’ has no member named ‘link’
  360 |         map->link = &obj->links.flatcg_ops;
      |            ^~
ninja: build stopped: subcommand failed.

[luigidematteis]

Hi @anh0516,
What version of bpftool are you using?
There seems to be a mismatch between the version of libbpf bundled with bpftool and the one installed on your system.

[anh0516]

Both the system bpftool 7.5 and the cloned bpftool fail when using system libbpf. They both work when using the cloned libbpf.

[hhoffstaette]

Both the system bpftool 7.5 and the cloned bpftool fail when using system libbpf. They both work when using the cloned libbpf.

This is a well-known problem when building skeletons created with a bpftool that has a newer libbpf built-in than the libbpf used for compiling. bpftool-7.5.0 uses a built-in libbpf-1.5.0, whereas this says your system libbpf is still 1.4.x. We've had the same issue in Gentoo - I know since I'm the maintainer 🥲
Fedora needs to ship matching versions. Alternatively you can try to install libbpf from Rawhide (no guarantees).