On Fri, Jan 29, 2021 at 1:41 PM Jakub Jelinek <jakub@xxxxxxxxxx> wrote: > > On Fri, Jan 29, 2021 at 04:32:32PM -0500, Arvind Sankar wrote: > > Given what Jakub is saying, i.e. it was previously impossible to get > > dwarf2 with gcc, and you get dwarf4 whether or not DEBUG_INFO_DWARF4 was > > It isn't impossible to get it, -gdwarf-2 works, it is just not a very good > choice (at least unless one knows some debug info consumer is not DWARF3 or > later ready). > Though, even gcc -gdwarf-2 will use many extensions from DWARF3 and later, > as long as there is no way to describe stuff in DWARF2. -gstrict-dwarf > option requests that no DWARF extensions are used. Playing with this in godbolt, it looks like the implicit default dwarf version changed from 2 to 4 in somewhere between the GCC 4.7.4 and 4.8.1 release. The precise version, and whether it was strictly that version or not doesn't matter much; the minimum supported version of GCC for building the kernel currently being 4.9 means that without specifying DEBUG_INFO_DWARF4, that all kernel developers regardless of toolchain and supported toolchain version have been building as DWARF v4 (implicitly, or explicitly). DWARF v2 is quite irrelevant then. Ok, so I think Arvind's suggestion of "make DEBUG_INFO_DWARF4 a menu option, just don't add a DEBUG_INFO_DWARF2" makes a lot of sense. Will drop DEBUG_INFO_DWARF2 in v7. -- Thanks, ~Nick Desaulniers
