On Tue, Nov 19, 2019 at 07:38:28AM -0600, Bjorn Helgaas wrote: > On Tue, Nov 19, 2019 at 03:17:04AM +0000, Nicholas Johnson wrote: > > I did just discover linux-next and I built it. Should I be doing this > > more often to help find regressions? > > Yes, if you build and run linux-next, that's a great service because > it helps find problems before they appear in mainline. Funnily enough, I just built Linux next-20191121 and it has a NULL dereference on start-up, which renders the system unusable. Can anybody else please confirm? I enabled most of the new options since the last linux-next a few days before. I did just compile on an i7-4770K using my USB SSD to boot. I suppose there is a tiny chance that the CPU had an error and produced bad code. It is not my machine. It was pegged at 100 degrees Celsius the whole time.... I do find it hard to believe that I am the first to notice it, though. I cannot find any bug reports on this. If this turns out to be an actual bug, is there a preferred way to report it? It is probably not from pci subsystem. I can do a bisect, but they consume a lot of time on a slow system. Here is a preliminary bug report (assuming you are meant to report linux-next bugs here): https://bugzilla.kernel.org/show_bug.cgi?id=205621 Cheers! Regards, Nicholas Johnson > > > I will now concentrate on fixing the problem where pci=nocrs does not > > ignore the bus resource. One motherboard I own gives 00-7e or similar, > > instead of 00-ff. The nocrs does not help, and I had to patch the kernel > > myself. Only acpi=off fixes the problem, while knocking out SMT (MADT), > > IOMMU (DMAR) and the ability to suspend without crashing. > > > > If you disagree that nocrs should override bus resource, then let me > > know and I will not attempt this. > > I guess the problem is that with "pci=nocrs", we ignore the MMIO and > I/O port resources from _CRS, but we still pay attention to bus number > resources in _CRS? That does sound like it would be unexpected > behavior. > > I *would* like to see the complete dmesg log because these _CRS > methods are pretty reliable because Windows relies on them as well, so > problems are frequently a result of Linux defects. If we can fix > Linux or automatically work around issues so users don't have to use > "pci=nocrs" explicitly, that's the best. > > Bjorn
