ci: libbpf-dev + conditional eBPF build (stub fallback without libbpf)

Author: Twyx22

.github/workflows/build.yml

@@ -18,7 +18,14 @@ jobs:
       - name: Install toolchain
         run: |
           sudo apt-get update
-          sudo apt-get install -y cmake g++ clang linux-libc-dev
+          sudo apt-get install -y cmake g++ clang libbpf-dev libelf-dev linux-libc-dev
+
+      - name: Compile eBPF object
+        run: |
+          # l'objet eBPF est compilé par le build CMake (clang -target bpf)
+          # avec les headers système ; clang sur GH Actions a besoin des
+          # includes asm de la libc
+          echo "compilé par CMake (voir configure)"
 
       - name: Configure
         run: |

CMakeLists.txt

@@ -45,22 +45,30 @@ target_include_directories(memflux_core PUBLIC include)
 target_link_libraries(memflux_core PUBLIC Threads::Threads bpf)
 
 # eBPF : l'objet est compilé si clang est disponible (optionnel au runtime)
+find_package(PkgConfig QUIET)
 find_program(CLANG_BPF clang)
-if(CLANG_BPF)
+if(PKG_CONFIG_FOUND)
+  pkg_check_modules(LIBBPF libbpf)
+endif()
+if(CLANG_BPF AND LIBBPF_FOUND)
   add_custom_command(
     OUTPUT ${CMAKE_BINARY_DIR}/ebpf_access.bpf.o
     COMMAND ${CLANG_BPF} -O2 -g -target bpf -D__TARGET_ARCH_x86
-            -I/usr/include -c ${CMAKE_SOURCE_DIR}/src/kern/ebpf_access.bpf.c
+            -I/usr/include/x86_64-linux-gnu -I/usr/include
+            -c ${CMAKE_SOURCE_DIR}/src/kern/ebpf_access.bpf.c
             -o ${CMAKE_BINARY_DIR}/ebpf_access.bpf.o
     DEPENDS src/kern/ebpf_access.bpf.c
     COMMENT "clang -target bpf: ebpf_access")
   add_custom_target(ebpf_obj ALL
     DEPENDS ${CMAKE_BINARY_DIR}/ebpf_access.bpf.o)
+  target_include_directories(memflux_core PUBLIC ${LIBBPF_INCLUDE_DIRS})
+  target_link_directories(memflux_core PUBLIC ${LIBBPF_LIBRARY_DIRS})
   target_compile_definitions(memflux_core PUBLIC
     EbpfObjectPath="${CMAKE_BINARY_DIR}/ebpf_access.bpf.o")
 else()
-  target_compile_definitions(memflux_core PUBLIC
-    EbpfObjectPath="")
+  # backend eBPF désactivé au runtime (EbpfObjectPath vide)
+  add_library(ebpf_stub OBJECT src/kern/ebpf_stub.cpp)
+  target_compile_definitions(memflux_core PUBLIC EbpfObjectPath="")
 endif()
 
 # ---------------------------------------------------------------------------

src/kern/ebpf.cpp

@@ -71,7 +71,6 @@ struct fault_val { __u64 minor; };
 std::map<pid_t, uint64_t> drain_faults(){
   std::map<pid_t, uint64_t> out;
   if(!g.map) return out;
-  int fd = bpf_map__fd(g.map);
   struct fault_key key = {}, next = {};
   struct fault_val val = {};
   while(bpf_map__get_next_key(g.map, &key, &next, sizeof(next)) == 0){

src/kern/ebpf_stub.cpp

@@ -0,0 +1,9 @@
+#include "memflux/ebpf.hpp"
+namespace memflux::ebpf {
+// stub : eBPF indisponible (libbpf ou clang -target bpf absent au build)
+bool available(){ return false; }
+bool load(){ return false; }
+void unload(){}
+bool loaded(){ return false; }
+std::map<pid_t, uint64_t> drain_faults(){ return {}; }
+} // namespace memflux::ebpf