Extern variable usage in BPF is different from traditional pure user space application. Recent discussion in linux bpf mailing list has two use cases where debug info types are required to use extern variables: - extern types are required to have a suitable interface in libbpf (bpf loader) to provide kernel config parameters to bpf programs. https://lore.kernel.org/bpf/CAEf4BzYCNo5GeVGMhp3fhysQ=_axAf=23PtwaZs-yAyafmXC9g@mail.gmail.com/T/#t - extern types are required so kernel bpf verifier can verify program which uses external functions more precisely. This will make later link with actual external function no need to reverify. https://lore.kernel.org/bpf/87eez4odqp.fsf@toke.dk/T/#m8d5c3e87ffe7f2764e02d722cb0d8cbc136880ed This patch added clang support to emit debuginfo for extern variables with a TargetInfo hook to enable it. Currently, only BPF target enables to generate debug info for extern variables. The emission of such debuginfo is disabled for C++ at this moment since BPF only supports a subset of C language. Emission with C++ can be enabled later if an appropriate use case is identified.

Extern variable usage in BPF is different from traditional pure user space application. Recent discussion in linux bpf mailing list has two use cases where debug info types are required to use extern variables: - extern types are required to have a suitable interface in libbpf (bpf loader) to provide kernel config parameters to bpf programs. https://lore.kernel.org/bpf/CAEf4BzYCNo5GeVGMhp3fhysQ=_axAf=23PtwaZs-yAyafmXC9g@mail.gmail.com/T/#t - extern types are required so kernel bpf verifier can verify program which uses external functions more precisely. This will make later link with actual external function no need to reverify. https://lore.kernel.org/bpf/87eez4odqp.fsf@toke.dk/T/#m8d5c3e87ffe7f2764e02d722cb0d8cbc136880ed This patch added clang support to emit debuginfo for extern variables with a TargetInfo hook to enable it. The debuginfo for the extern variable is emitted only if that extern variable is referenced in the current compilation unit. Currently, only BPF target enables to generate debug info for extern variables. The emission of such debuginfo is disabled for C++ at this moment since BPF only supports a subset of C language. Emission with C++ can be enabled later if an appropriate use case is identified. -fstandalone-debug permits us to see more debuginfo with the cost of bloated binary size. This patch did not add emission of extern variable debug info with -fstandalone-debug. This can be re-evaluated if there is a real need.

Extern variable usage in BPF is different from traditional pure user space application. Recent discussion in linux bpf mailing list has two use cases where debug info types are required to use extern variables: - extern types are required to have a suitable interface in libbpf (bpf loader) to provide kernel config parameters to bpf programs. https://lore.kernel.org/bpf/CAEf4BzYCNo5GeVGMhp3fhysQ=_axAf=23PtwaZs-yAyafmXC9g@mail.gmail.com/T/#t - extern types are required so kernel bpf verifier can verify program which uses external functions more precisely. This will make later link with actual external function no need to reverify. https://lore.kernel.org/bpf/87eez4odqp.fsf@toke.dk/T/#m8d5c3e87ffe7f2764e02d722cb0d8cbc136880ed This patch added clang support to emit debuginfo for extern variables with a TargetInfo hook to enable it. Currently,The debuginfo for the extern variable is emitted only BPF target enif that extern variables is referenced in the current compilation unit. Currently, only BPF target enables to generate debug info for extern variables. The emission of such debuginfo is disabled for C++ The emission ofat this moment since BPF only supports a subset of C language. Emission with C++ can be enabled later if an appropriate use case is identified. -fstandalone-debug permits us to see more debuginfo with the cost such debuginfo is disabled for C++ at this moment since BPF onlyof bloated binary size. This patch did not add emission of extern supports a subset of C languagevariable debug info with -fstandalone-debug. Emission with C++This can be enabledbe later if an appropriate use casre-evaluated if there is identifieda real need.