From 9b5d7b14d3e8d0553e0c994695f3a56e468bff3b Mon Sep 17 00:00:00 2001 From: Berkus Decker Date: Sun, 21 Feb 2021 00:38:47 +0200 Subject: [PATCH] Document TODO steps --- nucleus/src/arch/aarch64/memory/README.md | 48 +++++++++++++++++++++++ 1 file changed, 48 insertions(+) diff --git a/nucleus/src/arch/aarch64/memory/README.md b/nucleus/src/arch/aarch64/memory/README.md index 1e4943b..89cf420 100644 --- a/nucleus/src/arch/aarch64/memory/README.md +++ b/nucleus/src/arch/aarch64/memory/README.md @@ -9,3 +9,51 @@ a specific-size page. ---- For more information please re-read. + + + + + + + + + + + +---- + +# Plan +1. MMU tables - because we need separate memspaces for kernel and userspace + 1a. Allocate initial page tables + 1b. Map over available RAM sensibly + 1c. Create kernel's own mapping (TTBR_EL1) + +# What does the kernel MMU code support? +* mapping +* unmapping +* switching per-process mappings (virtspaces) +* virt2phys resolution +* direct phys access for kernel (TTBR_EL1 mapping to physmem) +* initial kernel memory allocation: for mapping tables and capnodes, for initial thread TCB and stacks + +# public api: + ARMMU invocations: + on page directory cap + cache maintenance (clean/invalidate/unify) + on page table cap + map + unmap + on small frame/frame caps + map + remap + unmap + cache maintenance (clean/invalidate/unify) + get address + on asid control cap + on asid pool cap + + +# Minimum Required Functionality (build from this) +* resolve VA to PA - resolving lets kernel access mapped process memory. + (start from the process' virtspace root - Page Directory) +* flush page, pd, pt, virtspace - will be important for thread switching