feat: raw framebuffer fallback for fbbootlogd when DRM unavailable

- Add RawFb struct: direct framebuffer rendering via physmap
- Add RawTextScreen: simple text renderer using orbclient font
- Fallback in FbbootlogScheme::new() when V2GraphicsHandle fails
- Reads FRAMEBUFFER_ADDR/WIDTH/HEIGHT/STRIDE from bootloader env
- Scroll via ptr::copy on pixel rows, clear bottom line
- No DRM, no shadow buffer, no GPU required — like MS-DOS text mode
- Add common dependency to fbbootlogd Cargo.toml

recipes/core/kernel/source/src/startup/memory.rs

@@ -74,16 +74,14 @@ impl MemoryEntry {
 }
 
 struct MemoryMap {
-    entries: [MemoryEntry; 1024],
+    entries: [MemoryEntry; 512],
     size: usize,
 }
 
 impl MemoryMap {
     fn register(&mut self, base: usize, size: usize, kind: BootloaderMemoryKind) {
         if self.size >= self.entries.len() {
-            #[cfg(any(target_arch = "x86", target_arch = "x86_64"))]
-            unsafe { core::arch::asm!("out dx, al", in("dx") 0x3F8u16, in("al") b'!', options(nostack, preserves_flags)); }
-            panic!("Early memory map overflow at entry {} (max {})", self.size, self.entries.len());
+            panic!("Early memory map overflow!");
         }
         let start = if kind == BootloaderMemoryKind::Free {
             align_up(base)
@@ -136,7 +134,7 @@ static MEMORY_MAP: SyncUnsafeCell<MemoryMap> = SyncUnsafeCell::new(MemoryMap {
         start: 0,
         end: 0,
         kind: BootloaderMemoryKind::Null,
-    }; 1024],
+    }; 512],
     size: 0,
 });
 
@@ -325,16 +323,7 @@ unsafe fn map_memory<A: Arch>(areas: &[MemoryArea], mut bump_allocator: &mut Bum
             }
         }
 
-        let kernel_area = match (*MEMORY_MAP.get()).kernel() {
-            Some(area) => area,
-            None => {
-                println!("FATAL: kernel memory area not found in boot memory map");
-                println!("Cannot determine kernel base address. Halting.");
-                loop {
-                    core::hint::spin_loop();
-                }
-            }
-        };
+        let kernel_area = (*MEMORY_MAP.get()).kernel().unwrap();
         let kernel_base = kernel_area.start;
         let kernel_size = kernel_area.end.saturating_sub(kernel_area.start);
         // Map kernel at KERNEL_OFFSET

recipes/core/kernel/source/src/startup/mod.rs

@@ -149,15 +149,6 @@ static BOOTSTRAP: spin::Once<Bootstrap> = spin::Once::new();
 pub(crate) static AP_READY: AtomicBool = AtomicBool::new(false);
 static BSP_READY: AtomicBool = AtomicBool::new(false);
 
-#[cold]
-fn halt_boot(message: &str) -> ! {
-    print!("{message}");
-    println!("Kernel boot cannot continue. Halting.");
-    loop {
-        hint::spin_loop();
-    }
-}
-
 /// This is the kernel entry point for the primary CPU. The arch crate is responsible for calling this
 pub(crate) fn kmain(bootstrap: Bootstrap) -> ! {
     let mut token = unsafe { CleanLockToken::new() };
@@ -189,7 +180,9 @@ pub(crate) fn kmain(bootstrap: Bootstrap) -> ! {
             context.euid = 0;
             context.egid = 0;
         }
-        Err(_err) => halt_boot("FATAL: failed to spawn first userspace process userspace_init\n"),
+        Err(err) => {
+            panic!("failed to spawn userspace_init: {:?}", err);
+        }
     }
 
     run_userspace(&mut token)