feat(shell): implement full interactive UNIX shell (osh), CMOS RTC, dual serial+PS2 keyboard input, and power management

kernel/src/mm/pfa.rs

@@ -7,11 +7,11 @@ use crate::kprintln;
 pub const PAGE_SIZE: usize = 4096;
 
 pub struct FrameAllocator {
-    bitmap: *mut u8,
-    bitmap_size_bytes: usize,
-    total_frames: usize,
-    free_frames: usize,
-    hhdm_offset: u64,
+    pub bitmap: *mut u8,
+    pub bitmap_size_bytes: usize,
+    pub total_frames: usize,
+    pub free_frames: usize,
+    pub hhdm_offset: u64,
 }
 
 unsafe impl Send for FrameAllocator {}
@@ -65,10 +65,8 @@ impl FrameAllocator {
         }
 
         self.bitmap = (bitmap_paddr + hhdm) as *mut u8;
-        // Initially mark all frames as used (1)
         core::ptr::write_bytes(self.bitmap, 0xFF, self.bitmap_size_bytes);
 
-        // Mark only truly usable RAM regions as free (0)
         self.free_frames = 0;
         for i in 0..entry_count {
             let entry = *entries.add(i);
@@ -82,7 +80,6 @@ impl FrameAllocator {
             }
         }
 
-        // Mark the bitmap memory itself as allocated
         let bitmap_start_frame = (bitmap_paddr as usize) / PAGE_SIZE;
         let bitmap_frame_count = (self.bitmap_size_bytes + PAGE_SIZE - 1) / PAGE_SIZE;
         for f in bitmap_start_frame..(bitmap_start_frame + bitmap_frame_count) {
@@ -92,7 +89,6 @@ impl FrameAllocator {
             }
         }
 
-        // Also protect low 1MiB
         let low_1mb_frames = 0x100000 / PAGE_SIZE;
         for f in 0..low_1mb_frames {
             if !self.test_bit(f) {
@@ -146,7 +142,6 @@ impl FrameAllocator {
                 self.set_bit(frame);
                 self.free_frames -= 1;
                 let paddr = (frame * PAGE_SIZE) as u64;
-                // Zero out the frame
                 unsafe {
                     let vaddr = (paddr + self.hhdm_offset) as *mut u8;
                     core::ptr::write_bytes(vaddr, 0, PAGE_SIZE);