Paging works :3

ableos/.cargo/config.toml

@@ -3,7 +3,7 @@ target = "./json_targets/x86_64-ableos.json"
 
 [unstable]
 build-std-features = ["compiler-builtins-mem"]
-build-std = ["core", "compiler_builtins"]
+build-std = ["core", "compiler_builtins", "alloc"]
 
 
 [target.'cfg(target_arch = "x86_64")']

ableos/src/arch/x86_64/memory.rs

@@ -1,3 +1,4 @@
+use bootloader::bootinfo::{MemoryMap, MemoryRegionType};
 use x86_64::{
 	structures::paging::{
 		FrameAllocator, Mapper, OffsetPageTable, Page, PageTable, PhysFrame, Size4KiB,
@@ -79,3 +80,33 @@ unsafe impl FrameAllocator<Size4KiB> for EmptyFrameAllocator {
 		None
 	}
 }
+
+pub struct BootInfoFrameAllocator {
+	memory_map: &'static MemoryMap,
+	next: usize,
+}
+
+impl BootInfoFrameAllocator {
+	pub unsafe fn init(memory_map: &'static MemoryMap) -> Self {
+		Self {
+			memory_map,
+			next: 0,
+		}
+	}
+
+	fn usable_frames(&self) -> impl Iterator<Item = PhysFrame> {
+		let regions = self.memory_map.iter();
+		let usable_regions = regions.filter(|r| r.region_type == MemoryRegionType::Usable);
+		let addr_range = usable_regions.map(|r| r.range.start_addr()..r.range.end_addr());
+		let frame_address = addr_range.flat_map(|r| r.step_by(4096));
+		frame_address.map(|addr| PhysFrame::containing_address(PhysAddr::new(addr)))
+	}
+}
+
+unsafe impl FrameAllocator<Size4KiB> for BootInfoFrameAllocator {
+	fn allocate_frame(&mut self) -> Option<PhysFrame<Size4KiB>> {
+		let frame = self.usable_frames().nth(self.next);
+		self.next += 1;
+		frame
+	}
+}

ableos/src/kmain.rs

@@ -57,13 +57,15 @@ pub fn kernel_main(boot_info: &'static BootInfo) -> ! {
 	let phys_mem_offset = VirtAddr::new(boot_info.physical_memory_offset);
 
 	let mut mapper = unsafe { memory::init(phys_mem_offset) };
-	let mut frame_allocator = memory::EmptyFrameAllocator;
+	let mut frame_allocator = unsafe {
+      memory::BootInfoFrameAllocator::init(&boot_info.memory_map)
+   };
 
-	let page = Page::containing_address(VirtAddr::new(0));
+	let page = Page::containing_address(VirtAddr::new(0xdeadbeaf000));
 	memory::create_example_mapping(page, &mut mapper, &mut frame_allocator);
 
 	let page_ptr: *mut u64 = page.start_address().as_mut_ptr();
-	unsafe { page_ptr.offset(400).write_volatile(0xf021_f077_f065_f04e) };
+	unsafe { page_ptr.offset(400).write_volatile(0xf021_f077_f065_804e) };
 
 	// stack_overflow();
 	// crate::arch::shutdown();

ableos/src/lib.rs

@@ -45,3 +45,4 @@ pub const RELEASE_TYPE: &str = "debug";
 #[cfg(not(debug_assertions))]
 /// A constant to check if the kernel is in release mode
 pub const RELEASE_TYPE: &str = "release";
+extern crate alloc;