https://sourceware.org/bugzilla/show_bug.cgi?id=28902
--- Comment #3 from Fangrui Song <i at maskray dot me> --- Hi Nick, sorry for my belated reply. I was on a trip. > > ld.bfd a.o -T insert-data.lds -T a.lds # ok > > ld.bfd a.o -T a.lds -T insert-data.lds # .data not found for insert > > > > # Remark: The order is puzzling. If ld processes -T in order, one will > > expect that `-T a.lds -T insert-data.lds` works and the other order fails. > > > I have not dug deeply into this, but I would guess that this happens because > the script parser is stack based, so it pulls out and processes > insert-data.lds before a.lds. But because semantic processing happens > before syntactic processing the INSERT in insert-data.lds has already stopped > the default linker script from being parsed, so the only possible definition > of .data comes from a.lds. > > I expect that using multiple -T options combined with INSERT directives is a > rare thing, which is why no-one has noticed this odd behaviour before. > Personally I think that the safest thing to do would be to just document the > behaviour, but not make any changes to the code. The order issue can be fixed by postponing the effects of INSERT after regular SECTIONS. Is it feasible? > > > ld.bfd a.o -T insert-note.lds --build-id # ok > > ld.bfd a.o -T a.lds -T insert-note.lds --build-id # .note.gnu.build-id not > > found for insert > > > This makes sense. The a.lds script does not define a .note.gnu.build-id > section, so there is nowhere for the INSERT AFTER in insert-note.lds to > attach to. > > When a.lds is omitted the default linker script is used instead and this does > define a .note.gnu.build-id section, which is why the INSERT AFTER works. > > > > ld.bfd a.o -T a.lds -dT insert-note.lds --build-id # ok > > > > # Remark: Why -T fails while -dT works is puzzling. If you specify > > --verbose, the used linker script is exactly the same. > > > It seems that -T and -dT are incompatible. In my tests it appears that the > -dT option is entirely ignored if -T is also used. This is a bug, but I am > concerned that fixing it might break scripts which unknowingly rely upon this > behaviour. So maybe it should be considered a documentation bug that the > incompatibility is not mentioned. >From Debian Code Search, https://codesearch.debian.net/search?q=%5B-%5DdT&literal=0 (-dT) has no result. --default-script seems unused as well, so I think changing the behavior of -dT probably does not matter. Making -dT work in the presence of -T probably makes more sense. > So overall I am inclined to think that these are both documentation bugs. Do > you agree ? -dT/--default-script seems unused (except the recent .note.package) and INSERT is super rare as well. I think there are some changes which may be worth making to make the behavior more reasonable and make the documentation more explainable to a reader. The current behaviors may be a bit difficult to describe in the documentation... -- You are receiving this mail because: You are on the CC list for the bug.
