On Fri, Jan 13, 2023 at 11:29:57AM -0700, jim.cromie@xxxxxxxxx wrote: > On Wed, Jan 11, 2023 at 4:09 PM Daniel Vetter <daniel@xxxxxxxx> wrote: > > > > On Mon, Dec 05, 2022 at 05:34:07PM -0700, Jim Cromie wrote: > > > Hi everyone, > > > > > > DRM_USE_DYNAMIC_DEBUG=y has a regression on rc-* > > > > > > Regression is due to a chicken-egg problem loading modules; on > > > `modprobe i915`, drm is loaded 1st, and drm.debug is set. When > > > drm_debug_enabled() tested __drm_debug at runtime, that just worked. > > > > > > But with DRM_USE_DYNAMIC_DEBUG=y, the runtime test is replaced with a > > > post-load enablement of drm_dbg/dyndbg callsites (static-keys), via > > > dyndbg's callback on __drm_debug. Since all drm-drivers need drm.ko, > > > it is loaded 1st, then drm.debug=X is applied, then drivers load, but > > > too late for drm_dbgs to be enabled. > > > > > > STATUS > > > > > > For all-loadable drm,i915,amdgpu configs, it almost works, but > > > propagating drm.debug to dependent modules doesnt actually apply, > > > though the motions are there. This is not the problem I want to chase > > > here. > > > > > > The more basic trouble is: > > > > > > For builtin drm + helpers, things are broken pretty early; at the > > > beginning of dynamic_debug_init(). As the ddebug_sanity() commit-msg > > > describes in some detail, the records added by _USE fail to reference > > > the struct ddebug_class_map created and exported by _DEFINE, but get > > > separate addresses to "other" data that segv's when used as the > > > expected pointer. FWIW, the pointer val starts with "revi". > > > > So I honestly have no idea here, linker stuff is way beyond where I have > > clue. So what's the way forward here? > > > > Ive fixed this aspect. > Unsurprisingly, it wasnt the linker :-} Awesome! > > The DEFINE/USE split does like the right thing to do at least from the > > "how it's used in drivers" pov. But if we're just running circles not > > quite getting there I dunno :-/ > > -Daniel > > > > Sending new rev next. > I think its getting close. Thanks a lot for keeping on pushing this. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch
