Bug#1145004: Mixed native platform and eBPF compile

Hi Michael,

the issue here is that the BPF compiler is made to consume the target 
architecture's glibc userspace headers as if it were compiling normal 
target userspace code.

bpf-gcc is compiling for the BPF target, while the build explicitly adds:

/usr/include/powerpc64-linux-gnu
/usr/include/sparc64-linux-gnu
/usr/include/x86_64-linux-gnux32

Those headers eventually pull in gnu/stubs.h, whose ABI selection 
expects multilib glibc headers that aren't installed in the build 
environment.

And should not be. Still you could provide them :).

1) I.e., you can add the (useless) target arch headers and make it compile:

Build-depend on g++-multilib

2) Drop CLAT on the affected architectures until upstream fixes the problem:

diff --git a/debian/rules b/debian/rules
index 76a5728a..064fc2e6 100755
--- a/debian/rules
+++ b/debian/rules
@@ -10,6 +10,17 @@ export PYTHON=/usr/bin/python3

  PPPD_PLUGIN_DIR := $(shell dh_ppp --plugin-dir)

+# GCC's BPF target currently gets the target's multiarch libc include
+# directory from NetworkManager's Meson build. On architectures where
+# the corresponding multilib glibc headers are not installed, this causes
+# bpf-gcc to include gnu/stubs.h and fail. Disable CLAT until the BPF
+# include-path handling is fixed upstream.
+ifeq ($(filter $(DEB_HOST_ARCH),ppc64 sparc64 x32),)
+CLAT_OPTION := -Dclat=true
+else
+CLAT_OPTION := -Dclat=false
+endif
+
  %:
         dh $@ --with ppp

@@ -54,7 +65,7 @@ override_dh_auto_configure:
                 -Dovs=true \
                 -Dqt=false \
                 -Debpf=false \
-               -Dclat=true \
+               $(CLAT_OPTION) \
                 -Dbpf-compiler=gcc \
                 -Dnbft=false \
                 -Dofono=true

3) Fix the upstream meson build. This is a bit out of scope for Debian 
packaging but if you wanna do upstream work:

Removing the (useless) cross-build logic in src/core/*bpf*/meson.build 
should™ fix it.

Kind regards,
Daniel