fix: accurate total system RAM calculation from all physical memory regions

kernel/src/arch/syscall.rs

@@ -323,7 +323,7 @@ pub extern "C" fn kernel_syscall_dispatcher(regs: &mut SyscallRegisters) {
                     let active = sched.threads.iter().filter(|t| t.state != crate::sched::thread::ThreadState::Unused).count();
 
                     (*out_ptr).uptime_ticks = sched.ticks;
-                    (*out_ptr).total_memory_bytes = pfa.usable_ram_bytes;
+                    (*out_ptr).total_memory_bytes = pfa.total_ram_bytes;
                     (*out_ptr).free_memory_bytes = (pfa.free_frames * PAGE_SIZE) as u64;
                     (*out_ptr).active_threads = active as u32;
                     (*out_ptr).cpu_cores = CORES_ONLINE.load(Ordering::Relaxed) as u32;

kernel/src/mm/pfa.rs

@@ -12,6 +12,7 @@ pub struct FrameAllocator {
     pub total_frames: usize,
     pub free_frames: usize,
     pub usable_ram_bytes: u64,
+    pub total_ram_bytes: u64,
     pub hhdm_offset: u64,
 }
 
@@ -24,6 +25,7 @@ pub static mut PFA: FrameAllocator = FrameAllocator {
     total_frames: 0,
     free_frames: 0,
     usable_ram_bytes: 0,
+    total_ram_bytes: 0,
     hhdm_offset: 0,
 };
 
@@ -38,15 +40,25 @@ impl FrameAllocator {
         let entry_count = (*memmap).entry_count as usize;
         let entries_ptr = (*memmap).entries;
         let mut max_paddr: u64 = 0;
+        let mut total_ram: u64 = 0;
         for i in 0..entry_count {
             let entry = *entries_ptr.add(i);
             let end = (*entry).base + (*entry).length;
             if end > max_paddr {
                 max_paddr = end;
             }
+            let t = (*entry).typ;
+            if t == LimineMemoryType::Usable as u64
+                || t == LimineMemoryType::BootloaderReclaimable as u64
+                || t == LimineMemoryType::KernelAndModules as u64
+                || t == LimineMemoryType::AcpiReclaimable as u64
+            {
+                total_ram += (*entry).length;
+            }
         }
 
         self.total_frames = (max_paddr as usize) / PAGE_SIZE;
+        self.total_ram_bytes = total_ram;
         self.bitmap_size_bytes = (self.total_frames + 7) / 8;
 
         // Find a usable region large enough to place the bitmap