On Wed, 13 Dec 2017, Thomas Gleixner wrote: > On Wed, 13 Dec 2017, Linus Torvalds wrote: > > > On Wed, Dec 13, 2017 at 8:41 AM, Thomas Gleixner <tglx@xxxxxxxxxxxxx> wrote: > > > > > > Definitely. That was fragile forever but puzzles me is that I can't figure > > > out what now causes that spurious interrupt to surface out of the blue. > > > > Perhaps just timing? > > That's what I'm trying to figure out right now, because that is the only > sensible explanation left. The whole machinery of suspend is exactly the > same with and without the vector changes. I instrumented all functions > involved and the picture is the same. I even do not see any fundamental > timing differences where one would say: That's it. > > What puzzles me even more is that in the range of commits I'm fiddling with > there is no other change than the vector management stuff and the point > where it breaks makes no sense at all. The point Maarten bisected it to > works nicely here, so that might just point to a very subtle timing issue. After doing more debugging on this it turns out that this looks like a legacy interrupt coming in. The vector number is always 55, which is legacy IRQ 7 as seen from the PIC. The corresponding IOAPIC interrupt pin is masked and vector 55 is completely unused. More questions than answers. Still investigating. Thanks, tglx
