build: autodetect ebpf support

.travis.yml

@@ -48,7 +48,7 @@ addons:
   coverity_scan:
     project:
       name: NetworkManager/NetworkManager
-    build_command_prepend: sh autogen.sh --with-systemd-logind=no --enable-more-warnings=no --disable-ovs --without-ebpf
+    build_command_prepend: sh autogen.sh --with-systemd-logind=no --enable-more-warnings=no --disable-ovs
     build_command: make -j4
     branch_pattern: .*coverity.*
 
@@ -114,7 +114,6 @@ script:
               -D ifcfg_rh=false \
               -D ibft=true \
               -D ifupdown=true \
-              -D ebpf=false \
               &&
           ninja -C build &&
           ninja -C build test
@@ -137,7 +136,6 @@ script:
               --enable-more-warnings=no \
               --enable-tests=yes \
               --with-crypto=$CRYPTO \
-              --without-ebpf \
               \
               --with-libnm-glib=yes \
               --with-iwd=yes \

configure.ac

@@ -520,12 +520,17 @@ esac
 
 # eBPF support
 AC_ARG_WITH(ebpf,
-            AS_HELP_STRING([--with-ebpf=yes|no], [Build with eBPF support (default: yes)]),
-            [], [with_ebpf=yes])
-if test "$with_ebpf" != "yes" -a "$with_ebpf" != "no"; then
-	AC_MSG_ERROR(--with-ebpf must be one of [yes, no])
+            AS_HELP_STRING([--with-ebpf=yes|no|auto], [Build with eBPF support (default: auto)]),
+            [], [with_ebpf=auto])
+if test "$with_ebpf" = "yes" -o "$with_ebpf" = "auto"; then
+	AC_CHECK_HEADER(linux/bpf.h, [have_ebpf=yes], [have_ebpf=no])
+else
+	have_ebpf=no
 fi
-AM_CONDITIONAL(WITH_EBPF, test "${with_ebpf}" = "yes")
+if test "$with_ebpf" = "yes" -a "$have_ebpf" = "no"; then
+	AC_MSG_ERROR([--with-ebpf=yes requires eBPF kernel header])
+fi
+AM_CONDITIONAL(WITH_EBPF, test "${have_ebpf}" = "yes")
 
 # SELinux support
 AC_ARG_WITH(selinux,
@@ -1362,5 +1367,5 @@ echo "  JSON validation for libnm: $enable_json_validation"
 echo "  crypto: $with_crypto (have-gnutls: $have_crypto_gnutls, have-nss: $have_crypto_nss)"
 echo "  sanitizers: $sanitizers"
 echo "  Mozilla Public Suffix List: $with_libpsl"
-echo "  eBPF: $with_ebpf"
+echo "  eBPF: $have_ebpf"
 echo

meson.build

@@ -423,6 +423,18 @@ if enable_selinux
 endif
 config_h.set10('HAVE_SELINUX', enable_selinux)
 
+# eBPF support
+ebpf_opt = get_option('ebpf')
+if ebpf_opt == 'false'
+  enable_ebpf = false
+else
+  enable_ebpf = true
+  if not cc.has_header('linux/bpf.h')
+    assert(ebpf_opt != 'true', 'eBPF requires kernel support')
+    enable_ebpf = false
+  endif
+endif
+
 # libaudit support
 libaudit = get_option('libaudit')
 enable_libaudit = libaudit.contains('yes')
@@ -994,4 +1006,5 @@ output += '  crypto: ' + crypto + ' (have-gnutls: ' + crypto_gnutls_dep.found().
 output += '  sanitizers: ' + get_option('b_sanitize') + '\n'
 output += '  Mozilla Public Suffix List: ' + enable_libpsl.to_string() + '\n'
 output += '  vapi: ' + enable_vapi.to_string() + '\n'
+output += '  ebpf: ' + enable_ebpf.to_string() + '\n'
 message(output)

meson_options.txt

@@ -41,7 +41,7 @@ option('libnm_glib', type: 'boolean', value: false, description: 'build legacy l
 option('nmcli', type: 'boolean', value: true, description: 'Build nmcli')
 option('nmtui', type: 'boolean', value: true, description: 'Build nmtui')
 option('bluez5_dun', type: 'boolean', value: false, description: 'enable Bluez5 DUN support')
-option('ebpf', type: 'boolean', value: true, description: 'Enable or disable eBPF support')
+option('ebpf', type: 'combo', choices : ['auto', 'true', 'false'], description: 'Enable eBPF support')
 
 # configuration plugins
 option('config_plugins_default', type: 'string', value: '', description: 'Default configuration option for main.plugins setting, used as fallback if the configuration option is unset')

shared/meson.build

@@ -24,7 +24,7 @@ shared_c_rbtree_dep = declare_dependency(
 )
 
 
-if get_option('ebpf')
+if enable_ebpf
     shared_n_acd_bpf_files = files('n-acd/src/n-acd-bpf.c')
 else
     shared_n_acd_bpf_files = files('n-acd/src/n-acd-bpf-fallback.c')