[pbowyer]

The kvm and tinykvm VMOD targets declare only C source files, so libtool links their shared objects using the C compiler. However, both targets also include the C++ libkvm.a and libtinykvm.a static archives.

Without an explicit C++ runtime dependency, loading either VMOD can fail when libstdc++ has not already been loaded into the Varnish process:

undefined symbol: _ZTVN10__cxxabiv117__class_type_infoE

I found this in EL10, where jemalloc does not pull in libstdc++. Debian and Ubuntu hid the missing dependency because libstdc++ is already present from their jemalloc packaging.

Adding -lstdc++ after the static archives gives both shared objects the dependency they require, independently of the host distribution's transitive dependencies.

[fwsGonzo]

Thanks!