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    Two simple IPC tests are passing. Still getting mysterious hang. · c667fea5
    Charlie Jacobsen authored and Vikram Narayanan's avatar Vikram Narayanan committed
    
    
    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: default avatarVikram Narayanan <vikram186@gmail.com>
    c667fea5