fix mmap for framebuffer

kernel/src/arch/x86_64/board/mod.rs

@@ -19,7 +19,7 @@ pub fn probe_fb_info(width : u32, height : u32, depth : u32) -> FramebufferResul
         yoffset: 0,
         depth: 24,
         pitch: 1024, // TOKNOW
-        bus_addr: 0xf000_0000,
+        bus_addr: 0xfd00_0000,
         screen_size: 1024 * 768 * 3,
     };
     Ok((fb_info, fb::ColorConfig::BGRA8888, KERNEL_OFFSET + 0xf000_0000))

kernel/src/drivers/gpu/fb.rs

@@ -172,6 +172,11 @@ impl Framebuffer {
         unsafe { self.buf.base_addr }
     }
 
+    #[inline]
+    pub fn bus_addr(&self) -> usize {
+        self.fb_info.bus_addr as usize
+    }
+
     /// Read pixel at `(x, y)`.
     #[inline]
     pub fn read(&self, x: u32, y: u32) -> u32 {

kernel/src/syscall/mem.rs

@@ -58,16 +58,19 @@ impl Syscall<'_> {
             info!("mmap path is {} ", &*file.path);
             match &*file.path {
                 "/dev/fb0" => {
-                    self.vm().push(
-                        addr,
-                        addr + len,
-                        prot.to_attr(),
-                        Linear::new(
-                            ( 0xfd00_0000 - addr ) as isize,
-                        ),
-                        "mmap_file",
-                    );
-                    info!("mmap for /dev/fb0");
+                    use crate::arch::board::fb::FRAME_BUFFER;
+                    if let Some(fb) = FRAME_BUFFER.lock().as_mut() {
+                        self.vm().push(
+                            addr,
+                            addr + len,
+                            prot.to_attr(),
+                            Linear::new(
+                                ( fb.bus_addr() - addr ) as isize,
+                            ),
+                            "mmap_file",
+                        );
+                        info!("mmap for /dev/fb0");
+                    }
                     return Ok(addr);
                 },
                 _ => {