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Achilleas Anagnostopoulos 1fc9d20ed2 Reserve and protect zereod frame when initializing vmm

This vmm package exports ReservedZeroedFrame which can be used to setup
a lazy physical page allocation scheme. This is implemented by mapping
ReservedZeroedFrame to each page in a virtual memory region using the
following flag combination: FlagPresent | FlagCopyOnWrite.

This has the effect that all reads from the virtual address region
target the contents of ReservedZeroedFrame (always returning zero). On
the other hand, writes to the virtual address region trigger a page
fault which is resolved as follows:
- a new physical frame is allocated and the contents of ReservedZeroedFrame
  are copied to it (effectively clearing the new frame).
- the page entry for the virtual address that caused the fault is
  updated to point to the new frame and its flags are changed to:
  FlagPresent | FlagRW
- execution control is returned back to the code that caused the fault

2017-06-22 19:17:19 +01:00

arch/x86_64

Enable page write protection for both kernel and user space

2017-06-22 06:24:30 +01:00

kernel

Reserve and protect zereod frame when initializing vmm

2017-06-22 19:17:19 +01:00

.gitignore

Update .gitignore

2017-03-23 06:50:13 +00:00

.travis.yml

Add lint Makefile target