fixed addr gdt, serial

xtask/src/mkimg.rs

@@ -1,8 +1,5 @@
 use crate::Context;
 
-const BLOCK_SIZE: u64 = 512;
-const PARTITION_ENTRY_SIZE: u64 = 128;
-
 // LBA 0: MBR
 // LBA 1: partition header
 // LBA 2..33: partition table entries