Date: Wed, 24 May 2017 18:33:07 -0400 From: Adam McDougall <mcdouga9@egr.msu.edu> To: royger@FreeBSD.org Cc: stable@freebsd.org Subject: Boot hang on Xen after r318347/(310418) Message-ID: <20170524223307.GS79337@egr.msu.edu>
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Hello, Recently I made a new build of 11-STABLE but encountered a boot hang at this state: http://www.egr.msu.edu/~mcdouga9/pics/r318347-smp-hang.png It is easy to reproduce, I can just boot from any 11 or 12 ISO that contains the commit. I compiled various svn revisions to confirm that r318347 caused the issue and r318346 is fine. With r318347 or later including the latest 11-STABLE, the system will only boot with one virtual CPU in XenServer. Any more cpus and it hangs. I also tried a 12 kernel from head this afternoon and I have the same hang. I had this issue on XenServer 7 (Xen 4.7) and XenServer 6.5 (Xen 4.4). I did most of my testing on 7. I also did much of my testing with a GENERIC kernel to try to rule out kernel configuration mistakes. When it hangs, the performance monitoring in Xen tells me at least one CPU is pegged. r318674 boots fine on physical hardware without Xen involved. Looking at r318347 which mentions EARLY_AP_STARTUP and later seeing r318763 which enables EARLY_AP_STARTUP in GENERIC, I tried adding it to my kernel but it turned the hang into a panic but with any number of CPUs: http://www.egr.msu.edu/~mcdouga9/pics/r318347-early-ap-startup-panic.png I think I verified that this happens with EARLY_AP_STARTUP before r318347 too so I'll assume it is a different problem. I may need to do some experimentation to figure out how to get the console to pass through hotkeys to drop into a kernel debugger. I could also try modifying the kernel config if I can make it print information about the hang. Is there anything else I can provide that might help? Would you prefer this be entered in a bugzilla report? Thanks.
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