Notices by Arnd Bergmann (arnd@society.oftrolls.com)

@KeyJ it nests min() multiple levels deep with the use of min3(), and each one expands its argument 20 times times now (up from 6 back in linux-6.6). This gets 8000 expansions for each of the arguments, plus a lot of extra bits with each expansion. PFN_DOWN(MAXMEM) contributes a bit to the initial size as well.

See https://pastebin.com/MmfWH7TM for the first few pages of it.

I had a feeling that kernel compilation got slower recently and tried to find the slowest file across randconfig builds. It turned out to be arch/x86/xen/setup.c, which takes 15 seconds to preprocess on a reasonably fast Apple M1 Ultra.

This all comes from one line "extra_pages = min3(EXTRA_MEM_RATIO * min(max_pfn, PFN_DOWN(MAXMEM)), extra_pages, max_pages - max_pfn);" that expands to 47MB of preprocessor output after commits 80fcac55385c..867046cc70277.

@LaF0rge The PCIe host bridge driver for that board doesn't translate I/O port resources, which means that many older PCI cards are impossible to use behind a bridge. I don't know if it's a hardware limitation or if the port window is left out from the device tree because it's never been tested.

@jmorris this returns a pointer to the inode of the third open file descriptor of the current thread, i.e stdout.