a323be3c8b
VeryPopularFunction (now GetPARPageInfo) takes a page number in the PAR and returns a bunch of info on it. The flags of the PTE are copied into cr5-cr7 of the condition register so that VMCalls can easily make decisions off of them. I had already figured out the bit flags of the PTEs Mac OS 9 uses when I reversed PagingFunc1. The definitions are in the end of the 'Area Definitions.txt' file I sent you a while ago. If you see a ' bltl cr5, VMDoSomethingWithTLB' (now RemovePageFromTLB) followed by a ' bltl cr5, major_0x09b40' (now RemovePTEFromHTAB), you know that the function is manipulating pages directly. RemovePageFromTLB clears a page from the TLB if it follows a VeryPopularFunction call. RemovePTEFromHTAB takes a page that is resident in the HTAB and removes its HTAB entry. cr5_lt is bit 20 (mask 0x800), which my notes tell me is set when the PTE is in the HTAB. Altogether, the sequence translates to 'if the page is in the HTAB, flush it from the TLB and delete its HTAB entry'. VMExchangePages uses this (twice) to make sure there are no race conditions when it is swapping the data in the pages. I still don't have proof, but I am very very strongly convinced that KDP.FlatPageListPointer is always equal to the PAR's PageMapArrayPtr. On an unrelated note, KCMapPage seems to always panic when called on an area where the PageMapArrayPtr is 2d. I have absolutely no idea why this happens, but it is bad news for MPMapper because the threshold for 2-dimensionality is around 1 MB. I would have to make 512 separate CreateArea calls to map all the memory without the NK panicking. I will have to look into this.
The PowerPC ROM for NewWorld Macs
This repo is part of the CDG5 project. It builds a 4 MB PowerPC Mac ROM by appending PowerPC code to a 68k Mac ROM (either the included dump, or one that you built yourself). The build result is a byte-perfect copy of the ROM inside the final "Mac OS ROM" release.
Fixing line endings
MPW requires old-style Mac line endings (CR), while Git works better with Unix line endings (LF). Git filters can be used to convert between the two. Files committed to the repo are "cleaned" (LF-ed), and then "smudged" (CR-ed) when they hit the working tree. After cloning, append these snippets to your Git config.
Append this to .git/config:
[filter "maclines"]
clean = LC_CTYPE=C tr \\\\r \\\\n
smudge = LC_CTYPE=C tr \\\\n \\\\r
Append this to .git/info/attributes:
* filter=maclines
*.* -filter
*.s filter=maclines
*.a filter=maclines
*.c filter=maclines
*.h filter=maclines
Finally, do a once-off "re-smudge":
rm -rf ../powermac-rom/*
git checkout .
Setting type and creator codes
Some MPW Tools require their input files to have the correct Mac OS file type, but Git does not save Mac OS type and creator codes. This shell script will give enough files a "TEXT" type to keep MPW happy.
sh SetFileTypes.sh
Building
This code is built with the Macintosh Programmer's Workshop (MPW), which runs on the Classic Mac OS. To satisfy the memory requirements of the build process, the MPW Shell should get a memory partition of at least 16 MB. Once you have MPW set up, the build process is not particularly fussy.
Not many computers run the Classic Mac OS any more. Here are a few workarounds:
- Just find a Mac running Mac OS 7.5-9.2. (Not much fun if it's also your test machine.)
- Use the Classic environment on a PowerPC Mac running Mac OS X 10.4 or earlier. (A small PowerBook or iBook is perfect.)
- Use EMPW ("Emulated MPW"), a package of command-line tools, emulators and OS images that lets you run MPW commands straight from your macOS Terminal. This is my preferred solution.
Once MPW is set up, the build command is:
EasyBuild
Using EMPW, that's:
empw -b EasyBuild
The 4 MB image will be at BuildResults/PowerROM.
What's next?
On NewWorld Macs, this image is extracted into RAM from a "Mac OS ROM" file at boot. Use https://github.com/elliotnunn/newworld-rom to build such a file.