"Jose E. Marchesi via Gcc" <gcc@gcc.gnu.org> writes: > Hello people! > > This year we will be having a kernel BoF at Cauldron. It is scheduled > for Saturday from 15:30 to 16:30. There will be several kernel > maintainers and hackers in attendance, and the goal of the BoF is to > discuss and collect feedback about several toolchain-related issues that > are of current interest for the kernel. The output of the discussions > and the feedback collected will then be used as a basis for further > discussions at the Linux Plumbers conference that will be held the next > week in Vienna. The idea is to get kernel and toolchain hackers > together and advance on these topics. > > Find below some of the topics we will be discussing. Many of them are > relevant to GCC, and we ask you to consider attending if you are coming > to the Cauldron. The list of topics is of course not closed, and you > are very welcome to bring your own, specially if your work would benefit > from feedback from the kernel hackers. > > - LTO and inline asm symbols > > A lot of assembler statements reference C symbols, which need to be > externally_visible and global for GCC LTO, otherwise they can end up in the > wrong asm file and cause missing symbols. > > Goal of the discussion: > > Provide an assessment of the reported problem, and discuss the two > alternatives already proposed in the bugzillas below: one ad-hoc solution > based on parsing symbol references in inline asm strings, another is to > allow top-level extended asm that can get input arguments. > > References: > > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=107779 > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=41045
We didn't end up having time to discuss this in the BoF *but* the videos from this year's Cauldron are now available at https://www.youtube.com/@gnutoolscauldron7666. It looks like Honza's IPA/LTO/FDO BoF did cover this for a while and some interesting ideas came up -- see https://youtu.be/bWH4_in2s0o?t=1450 onwards. A lot of the discussion was around the biggest blocker (handling global asm) and the format of some possible gas extensions & diagnostics required. thanks, sam
