Add notes on missing features for kernel remapping

1 files changed, 2 insertions, 0 deletions

diff --git a/arch/x86_64/include/arch/memory/paging/kernel_mapper.hpp b/arch/x86_64/include/arch/memory/paging/kernel_mapper.hpp
index f980451..897ae06 100644
--- a/arch/x86_64/include/arch/memory/paging/kernel_mapper.hpp
+++ b/arch/x86_64/include/arch/memory/paging/kernel_mapper.hpp
@@ -48,6 +48,8 @@ namespace teachos::arch::memory::paging
       inactive_page_table new_table{frame.value(), active_table, temporary_page};
       remap_elf_kernel_sections(new_table, temporary_page, active_table);
       auto const old_table = switch_active_page_table(new_table);
+      // Turn old level 4 page table, mapped by assembler code into stack guard page.
+      // Only works if the identity mapped page tables by assembler are right above the stack.
       auto const old_level_4_page =
           virtual_page::containing_address(old_table.page_table_level_4_frame.start_address());
       active_table.unmap_page(allocator, old_level_4_page);