diff --git a/VKernel/Kernel/drivers/fs/fat32/fat32_types.vp b/VKernel/Kernel/drivers/fs/fat32/fat32_types.vp
index 75f89c5..71eac35 100644
--- a/VKernel/Kernel/drivers/fs/fat32/fat32_types.vp
+++ b/VKernel/Kernel/drivers/fs/fat32/fat32_types.vp
@@ -360,6 +360,13 @@ class volinfo:
 		res2: DRESULT = diskio.read(self.pdrv, win_addr, t.CUInt32T(abs_sector), 1)
 		self.lock.unlock()
 		if res2 != DRESULT.RES_OK: return FRESULT.FR_DISK_ERR
+		# [DIAG] 定位 win[0..1] 被清零（L271 win=00 00 20...）：区分读错扇区
+		# vs 读后被覆盖——打印 abs_sector 与读后 win 前 4 字节。
+		_dwr: t.CArray[t.CChar, 96]
+		viperlib.snprintf(c.Addr(_dwr), 96, "[wr] sec=%lx abs=%lx hid=%lx w0=%02x %02x %02x %02x\n",
+			sector, abs_sector, t.CUInt64T(self.hidden_sectors),
+			self.win[0], self.win[1], self.win[2], self.win[3])
+		serial.puts(c.Addr(_dwr))
 		self.winsect = sector
 		return FRESULT.FR_OK
 
diff --git a/VKernel/Kernel/execrunner/elf.vp b/VKernel/Kernel/execrunner/elf.vp
index fedc766..a2b4aca 100644
--- a/VKernel/Kernel/execrunner/elf.vp
+++ b/VKernel/Kernel/execrunner/elf.vp
@@ -175,6 +175,16 @@ def load_elf(path: t.CConst | str, do_map: t.CInt = 1) -> t.CVoid | t.CPtr:
 
     if ehdr.e_machine != EM_X86_64:
         serial.puts("[elf] not x86_64\n")
+        # [DIAG] e_machine 错：dump ehdr 前 24 字节（read_len=64 正确但内容错）
+        _dbg_em: t.CArray[t.CChar, 128]
+        viperlib.snprintf(c.Addr(_dbg_em), 128,
+            "[elf] ehdr=%02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x rl=%lu\n",
+            ehdr_buf[0], ehdr_buf[1], ehdr_buf[2], ehdr_buf[3],
+            ehdr_buf[4], ehdr_buf[5], ehdr_buf[6], ehdr_buf[7],
+            ehdr_buf[8], ehdr_buf[9], ehdr_buf[10], ehdr_buf[11],
+            ehdr_buf[12], ehdr_buf[13], ehdr_buf[14], ehdr_buf[15],
+            ehdr_buf[16], ehdr_buf[17], ehdr_buf[18], ehdr_buf[19], read_len)
+        serial.puts(c.Addr(_dbg_em))
         fat32.close(fp)
         return None