On 25/08/15 16:45, Daniel Vetter wrote: > When the usual fbcon legacy options are enabled we have > ->register_framebuffer > ->fb notifier chain calls into fbcon > ->fbcon sets up console on new fbi > ->fbi->set_par > ->drm_fb_helper_set_par exercises full kms api > > And because of locking inversion hilarity all of register_framebuffer > is done with the console lock held. Which means that the first time on > driver load we exercise _all_ the kms code (all probe paths and > modeset paths for everything connected) is under the console lock. > That means if anything goes belly-up in that big pile of code nothing > ever reaches logfiles (and the machine is dead). > > Usual tactic to debug that is to temporarily remove those console_lock > calls to be able to capture backtraces. I'm fed up writing this patch > and recompiling kernels. Hence this patch here to add an unsafe, > kernel-taining option to do this at runtime. I think this was never merged. This was part 4 of 4, were there dependencies or...? Should I apply this for 4.5? But then... I think my issues with console lock have been later at runtime, not at register. Maybe we need a module option to disable the console lock altogether. I wonder how much havoc that might create, though. Tomi
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