Meanwhile, seeing what @marcan42 just did...
Having a Mach-O header present through a linker script for an _ELF_ linker is… let’s say quite unique.
-
Linux ARM64 kernels are flat files even though Linux is an ELF system :-) clang "shouldn't be a big hurdle" but it's a bigger hurdle than the aarch64-linux-gnu-gcc that every person compiling anything on arm64 linux already has available.
The reason why OS kernels don't need to be full-fat executable formats is that they only need a tiny fraction of the features of such formats. As far as I can tell the only reason for Darwin to be using mach-o is so iBoot can preconfigure some KTRR stuff.
-
-
Much more than that, it’s that the kernel cache is a bundle with the kernel extensions included too.
-
Those kexts are prelinked into one text blob these days though, which at that point isn't unlike Linux's built-in kernel modules. Linux uses tons of internal sections to implement stuff like that, but none of it needs to be visible at the bootloader ABI level.
- Show replies
New conversation -
-
-
And Mach-O is a particularly ill-suited executable container for an OS kernel, because unlike ELF it has no notion of virt vs phys addresses, so the Darwin ARM64 boot ABI ends up being a mess of making up fake virtual addresses and computing kernel base/size based on heuristics.
-
Heuristics?! Are you talking about iBoot here, or your Linux handoff thing? Because you will undoubtedly have come across this thing... kinda gives you all the info you need, no?pic.twitter.com/l4GNFcG4VO
End of conversation
New conversation -
Loading seems to be taking a while.
Twitter may be over capacity or experiencing a momentary hiccup. Try again or visit Twitter Status for more information.