On 10.10.23 02:20, Andrew Morton wrote:
On Sun, 08 Oct 2023 09:54:22 +1100 Michael Ellerman <mpe@xxxxxxxxxxxxxx> wrote:
I don't know why powerpc's PTE_INDEX_SIZE is variable.
To allow a single vmlinux to boot using either the Hashed Page Table
MMU, or Radix Tree MMU, which have different page table geometry.
That's a pretty crucial feature for distros, so that they can build a
single kernel to boot on Power8/9/10.
Dumb question: why can't distros ship two kernels and have the boot
loader (or something else) pick the appropriate one?
One answer I keep hearing over and over again is "test matrix
explosion". So distros only do it when unavoidable: for example, when
differing PAGE_SIZE is required (e.g., 4k vs 64k) or we're dealing with
RT support (RT vs !RT).
--
Cheers,
David / dhildenb
