diff --git a/os/Makefile b/os/Makefile
index 7499dd60..92ae26fb 100644
--- a/os/Makefile
+++ b/os/Makefile
@@ -25,10 +25,10 @@ DISASM ?= -x
 build: env $(KERNEL_BIN)
 
 env:
-	rustup component add rust-src
-	rustup component add llvm-tools-preview
-	cargo install cargo-binutils
-	rustup target add riscv64gc-unknown-none-elf
+	(rustup component list | grep "rust-src") || rustup component add rust-src
+	(rustup component list | grep "llvm-tools-preview") || rustup component add llvm-tools-preview
+	(which rust-objdump) || cargo install cargo-binutils
+	(rustup target list | grep "riscv64gc-unknown-none-elf") || rustup target add riscv64gc-unknown-none-elf
 
 $(KERNEL_BIN): kernel
 	@$(OBJCOPY) $(KERNEL_ELF) --strip-all -O binary $@
@@ -58,11 +58,11 @@ ifeq ($(BOARD),qemu)
 		-device loader,file=$(KERNEL_BIN),addr=$(KERNEL_ENTRY_PA)
 else
 	@cp $(BOOTLOADER) $(BOOTLOADER).copy
-	@dd if=$(KERNEL_BIN) of=$(BOOTLOADER).copy bs=128K seek=1
+	@dd if=$(KERNEL_BIN) of=$(BOOTLOADER).copy bs=131072 seek=1
 	@mv $(BOOTLOADER).copy $(KERNEL_BIN)
 	@sudo chmod 777 $(K210-SERIALPORT)
 	python3 $(K210-BURNER) -p $(K210-SERIALPORT) -b 1500000 $(KERNEL_BIN)
-	miniterm --eol LF --dtr 0 --rts 0 --filter direct $(K210-SERIALPORT) 115200
+	python3 -m serial.tools.miniterm --eol LF --dtr 0 --rts 0 --filter direct $(K210-SERIALPORT) 115200
 endif
 
 debug: build