Function create_empty_pagetable

kernel/src/memory.rs:111–128

Create a new page table Returns ------- - A pointer to the PageTable (virtual address in kernel mapped pages) - The physical address which can be written to cr3

()

/// - The physical address which can be written to cr3
///
fn create_empty_pagetable() -> (*mut PageTable, u64) {
    // Need to borrow as mutable so that we can allocate new frames
    // and so modify the frame allocator
    let memory_info = unsafe {MEMORY_INFO.as_mut().unwrap()};

    // Get a frame to store the level 4 table
    let level_4_table_frame = memory_info.frame_allocator.allocate_frame().unwrap();
    let phys = level_4_table_frame.start_address(); // Physical address
    let virt = memory_info.physical_memory_offset + phys.as_u64(); // Kernel virtual address
    let page_table_ptr: *mut PageTable = virt.as_mut_ptr();

    // Clear all entries in the page table
    unsafe {
        (*page_table_ptr).zero();
    }

    (page_table_ptr, phys.as_u64())
}

/// Copy a set of pagetables
fn copy_pagetables(level_4_table: &PageTable) -> (*mut PageTable, u64) {