Implement shadow page tables [2/3]

1. Merge remaining parts of mmu.cpp change that were skipped in d15ce06d
2. Extract KPTI constants into a private header; we don't need or want to
   make the x86 aspace code depend on lib/code_patching publically.
3. Minor build fixes
4. Switch X86PageTableBase::Init() -> virtual; we expect each type of page
   table implementation to override it.
5. Disable multi-page page table allocation; we are going to replace it,
   as contiguous allocations at runtime are disfavored.

ZX-1528 #comment Implement PML4 shadowing and swapping
ZX-1526

Tested:
* Builds, but does not boot (as expected)
7 files changed
tree: 010ddc9094730ae84b89881254001953c2ee721c
  1. .clang-format
  2. .clang-tidy
  3. .dir-locals.el
  4. .gitattributes
  5. .gitignore
  6. .gn
  7. .style.yapf
  8. AUTHORS
  9. BUILD.gn
  10. CODE_OF_CONDUCT.md
  11. CONTRIBUTING.md
  12. LICENSE
  13. OWNERS
  14. PATENTS
  15. README.md
  16. boards/
  17. build/
  18. buildtools/
  19. bundles/
  20. docs/
  21. examples/
  22. garnet/
  23. peridot/
  24. products/
  25. rustfmt.toml
  26. scripts/
  27. sdk/
  28. src/
  29. third_party/
  30. tools/
  31. zircon/
README.md

Fuchsia

Pink + Purple == Fuchsia (a new operating system)

What is Fuchsia?

Fuchsia is a modular, capability-based operating system. Fuchsia runs on modern 64-bit Intel and ARM processors.

Fuchsia is an open source project with a code of conduct that we expect everyone who interacts with the project to respect.

How can I build and run Fuchsia?

See Getting Started.

Where can I learn more about Fuchsia?

See fuchsia.dev.