Nx bit support + minor fixes

[DixelU]

That's like the second attempt at cracking this thing 🐈, and there's still some things to work on left.

The good part:

• Implemented the NX bit itself.
  • And the most minimal test in NASM possible.
• Faced the issue with RSVD Page faults being unimplemented (which prevented the boot up of linux distributions and windows 7) - implemented though I did not test it though properly yet.
• Did fix some funky stuff IDE was suggesting in the NASM tests run script along the support for NX test itself ... and god knows what else (I did pull AI for that one, I'll later look into reverting most of its changes though)
• Tests - all seemed to complete with return code 0, and I was able to load a small build of windows 7 (from CD rom, later bout that) with NX bit enabled:
  

The problems left (and noticed)

• Standard windows 7 installation did not boot up being stuck at

  16:06:52+762 [ACPI] ACPI raise irq
  16:06:52+762 [CPU ] No route: level interrupt and remote IRR still set
  

  repeating endlessly. Did waste an entire evening on that one, without a thing out of it. Only a cut down version did boot up properly. Not sure why.
• Whilst comparing how systems boot on that branch with currently released version of v86 - I did notice that in release the system hangs seemingly randomly inside net2k implementation (might need a separate issue for that) - cannot reproduce rn, but I'll create a separate issue once I face it again.
• The mess in test scripts.

[YD711YT]

Will windows 8 work?

[DixelU]

Will windows 8 work?

I'll check it out this weekend

[DimaThenekov]

Wow, this is great! I think Windows 7+ bootloaders require something else besides the NX bit. I couldn't start Windows 8 and 10 😢...

[DimaThenekov]

In particular, I get a #GP exception