Charles Jacobsen authored Feb 23, 2016 and Vikram Narayanan committed Oct 26, 2016

Couple interesting issues here:

   1 - Syscalls were breaking without "asm volatile". I tried
       just plain "asm" to be more compiler-friendly (I guess that
       is more friendly), but the compiler optimized away entire
       vmcall's, haha.
   2 - Guest virtual page table set up was way off for the pud (wasn't
       pointing to the pmd's, and some of the surrounding address
       arithmetic was bad). It's still bad (too specific for x86_64
       perhaps), but that's acceptable for now.
   3 - This was the most interesting one. I didn't even think that
       when we build liblcd (the .a file), the kernel doesn't think
       we're building a kernel module, so THIS_MODULE expands to
       NULL. In order to fix this, I manually set the MODULE macro
       (via a -D cc flag) so that the module.h macros expand as
       expected (we will always link liblcd.a with a kernel module,
       so e.g. struct module __this_module will always be defined).