On Thu, Feb 14, 2019 at 9:38 PM Y Song [off-list ref] wrote:

On Mon, Feb 11, 2019 at 4:48 PM Joe Stringer [off-list ref] wrote:

quoted

Support loads of static 32-bit data when BPF writers make use of
convenience macros for accessing static global data variables. A later
patch in this series will demonstrate its usage in a selftest.

As of LLVM-7, this technique only works with 32-bit data, as LLVM will
complain if this technique is attempted with data of other sizes:

    LLVM ERROR: Unsupported relocation: try to compile with -O2 or above,
    or check your static variable usage

A little bit clarification from compiler side.
The above compiler error is to prevent people use static variables since current
kernel/libbpf does not handle this. The compiler only warns if .bss or
.data section
has more than one definitions. The first definition always has section offset 0
and the compiler did not warn.

ahh. missed that while playing with .s output.
when target is asm clang doesn't complain.
let's relax this llvm error.
will set of existing relocation be enough to generate
properly formed .o ?
or we need to define a new one?