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Working on moving Linux's mm into lcd's. I gave up trying to debug the hang. Confirmed the pages for the lcd's vm are the ones I expect. Turned on red zones. All tests are passing. Hang happens after insmod/rmmod of the lcd module about 10 - 20 times, it varies. Sometimes one core just silently dies / doesn't even respond to an NMI. Sometimes the ethernet driver complains (this could be an unrelated bug that was fixed upstream). Few things in this commit: 1 ===== Updated documentation in Documentation/lcd-domains/. 2 ===== Baby version of lib kernel, inside arch/x86/lcd-domains/liblcd.c. Unfortunately due to the recursive make, this needs to be textually included inside the modules destined for lcd's, for now. 3 ===== Added new test modules and modified directory structure and build system. See documentation in Documentation/lcd-domains. 4 ===== A few tweaks to the nmi handler to print a backtrace. May remove that in the future, as it's probably not safe to do inside an nmi handler (but if we're in that error state, we might be desperate to know what's happening ...). 5 ===== Changed interrupt handling in arch-dependent code. The KVM code we were using is probably wrong for 64-bit - it doesn't properly switch stacks, etc., which is super important for 64-bit and may be impossible to emulate in software. I think this could be stale code inside KVM, but not sure. Dune doesn't use it. KVM doesn't ack external interrutps on vm exit, so I think this interrupt emulation code is always skipped (at least for non-nested VMs). Instead, we're not ack'ing interrupts on exit, and letting the native code do the right thing, like Dune. I was thinking this might be the source of the bad hang (stack overflow, e.g.), but not true. Conflicts: include/linux/sched.h kernel/watchdog.c virt/lcd-domains/lcd-cspace-tests2.c Resolved-by: Vikram Narayanan <vikram186@gmail.com>
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