diff --git a/VKernel/Kernel/drivers/fs/fat32/fat32_types.vp b/VKernel/Kernel/drivers/fs/fat32/fat32_types.vp
index 1d0453d..33fce2d 100644
--- a/VKernel/Kernel/drivers/fs/fat32/fat32_types.vp
+++ b/VKernel/Kernel/drivers/fs/fat32/fat32_types.vp
@@ -262,6 +262,10 @@ def sfn_from_lfn(lfn: t.CConst | t.CChar | t.CPtr, sfn: t.CChar | t.CPtr):
 		sfn[6] = '~'
 		sfn[7] = '1'
 	sfn[11] = 0
+	# [DIAG] 定位 sfn 缺扩展名（Hello 显示 HELLO 空格）：打印 name 与 dot_pos/ext_i
+	_dsf: t.CArray[t.CChar, 80]
+	viperlib.snprintf(c.Addr(_dsf), 80, "[sfn2] dot=%d i=%d ext=%d sfn=%.11s\n", dot_pos, i, ext_i, sfn)
+	serial.puts(c.Addr(_dsf))
 
 def sfn_to_str(sfn: t.CConst | t.CChar | t.CPtr, out: t.CChar | t.CPtr):
 	i: t.CInt = 0