diff --git a/Makefile b/Makefile
index 11e11cd..399afff 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,8 @@
 K=kernel
 U=user
 
+BOOTLOADER = ./external/rustsbi-qemu.bin
+
 OBJS = \
   $K/entry.o \
   $K/start.o \
@@ -163,7 +165,7 @@ ifndef CPUS
 CPUS := 3
 endif
 
-QEMUOPTS = -machine virt -bios none -kernel $K/kernel -m 128M -smp $(CPUS) -nographic
+QEMUOPTS = -machine virt -bios $(BOOTLOADER) -kernel $K/kernel -m 128M -smp $(CPUS) -nographic
 QEMUOPTS += -global virtio-mmio.force-legacy=false
 QEMUOPTS += -drive file=fs.img,if=none,format=raw,id=x0
 QEMUOPTS += -device virtio-blk-device,drive=x0,bus=virtio-mmio-bus.0
@@ -185,10 +187,12 @@ fmt:
 	cd ./rs_src/xv6/ && make fmt
 
 .PHONY: rs-os
+RS_KERNEL := ./rs_src/xv6/xv6-kernel/target/riscv64gc-unknown-none-elf/release/xv6-kernel
 rs-os: $(OBJS) $K/kernel.ld $U/initcode
 	cd ./rs_src/xv6/ && make all
-RS_KERNEL := ./rs_src/xv6/xv6-kernel/target/riscv64gc-unknown-none-elf/release/xv6-kernel
-RS_QEMUOPTS = -machine virt -bios none -kernel $(RS_KERNEL) -m 128M -smp $(CPUS) -nographic
+	rust-objcopy --binary-architecture=riscv64 $(RS_KERNEL) --strip-all -O binary $(RS_KERNEL).bin
+RS_QEMUOPTS = -machine virt -bios $(BOOTLOADER) -device loader,file=$(RS_KERNEL).bin,addr=0x80200000
+RS_QEMUOPTS += -m 128M -smp $(CPUS) -nographic
 RS_QEMUOPTS += -global virtio-mmio.force-legacy=false
 RS_QEMUOPTS += -drive file=fs.img,if=none,format=raw,id=x0
 RS_QEMUOPTS += -device virtio-blk-device,drive=x0,bus=virtio-mmio-bus.0
@@ -196,6 +200,10 @@ RS_QEMUOPTS += -device virtio-blk-device,drive=x0,bus=virtio-mmio-bus.0
 rs-qemu: rs-os fs.img
 	$(QEMU) $(RS_QEMUOPTS)
 
+rs-qemu-gdb: rs-os .gdbinit fs.img
+	@echo "*** Now run 'gdb' in another window." 1>&2
+	$(QEMU) $(RS_QEMUOPTS) -S $(QEMUGDB)
+
 debug-sym: $K/kernel rs-os
 	$(OBJDUMP) -t $K/kernel    | sed '1,/SYMBOL TABLE/d; s/ .* / /; /^$$/d' > debug_c.sym
 	$(OBJDUMP) -t $(RS_KERNEL) | sed '1,/SYMBOL TABLE/d; s/ .* / /; /^$$/d' > debug_rs.sym
@@ -203,3 +211,9 @@ debug-sym: $K/kernel rs-os
 
 show-debug-sym: debug-sym
 	diff -u --color debug_c.sym debug_rs.sym
+
+conn-gdb:
+	(gdb \
+		-ex 'file $(RS_KERNEL)' \
+		-ex 'set arch riscv:rv64' \
+		-ex 'target remote localhost:${GDBPORT}')
diff --git a/external/rustsbi-qemu.bin b/external/rustsbi-qemu.bin
new file mode 100644
index 0000000..463cfa9
Binary files /dev/null and b/external/rustsbi-qemu.bin differ
diff --git a/kernel/entry.S b/kernel/entry.S
index 5ab365e..1d7975d 100644
--- a/kernel/entry.S
+++ b/kernel/entry.S
@@ -3,19 +3,17 @@
         # kernel.ld causes the following code to
         # be placed at 0x80000000.
 .section .text
-.global _entry
-_entry:
-        # set up a stack for C.
-        # stack0 is declared in start.c,
-        # with a 4096-byte stack per CPU.
-        # sp = stack0 + (hartid * 4096)
-        la sp, stack0
-        li a0, 1024*4
-        csrr a1, mhartid
-        addi a1, a1, 1
-        mul a0, a0, a1
-        add sp, sp, a0
-        # jump to start() in start.c
-        call start
+.global _start
+_start:
+    la sp, boot_stack_top
+    call main
+
+    .section .bss.stack
+    .globl boot_stack_lower_bound
+boot_stack_lower_bound:
+    .space 4096 * 16
+    .globl boot_stack_top
+boot_stack_top:
+
 spin:
         j spin
diff --git a/kernel/kernel.ld b/kernel/kernel.ld
index ee04f22..c906469 100644
--- a/kernel/kernel.ld
+++ b/kernel/kernel.ld
@@ -1,13 +1,13 @@
 OUTPUT_ARCH( "riscv" )
-ENTRY( _entry )
+ENTRY( _start )
 
 SECTIONS
 {
   /*
-   * ensure that entry.S / _entry is at 0x80000000,
+   * ensure that entry.S / _start is at 0x80000000,
    * where qemu's -kernel jumps.
    */
-  . = 0x80000000;
+  . = 0x80200000;
 
   .text : {
     *(.text .text.*)
diff --git a/kernel/main.c b/kernel/main.c
index dd35d9c..c6da4a5 100644
--- a/kernel/main.c
+++ b/kernel/main.c
@@ -14,19 +14,32 @@ void c_main() {
     printf("\n");
     printf("xv6 kernel is booting\n");
     printf("\n");
-    kinit();            // physical page allocator
-    kvminit();          // create kernel page table
-    kvminithart();      // turn on paging
-    procinit();         // process table
-    trapinit();         // trap vectors
-    trapinithart();     // install kernel trap vector
-    plicinit();         // set up interrupt controller
-    plicinithart();     // ask PLIC for device interrupts
-    binit();            // buffer cache
-    iinit();            // inode table
-    fileinit();         // file table
-    virtio_disk_init(); // emulated hard disk
-    userinit();         // first user process
+    kinit();
+    printf("[OK] physical page allocator\n");
+    kvminit();
+    printf("[OK] create kernel page table\n");
+    kvminithart();
+    printf("[OK] turn on paging\n");
+    procinit();
+    printf("[OK] process table\n");
+    trapinit();
+    printf("[OK] trap vectors\n");
+    trapinithart();
+    printf("[OK] install kernel trap vector\n");
+    plicinit();
+    printf("[OK] set up interrupt controller\n");
+    plicinithart();
+    printf("[OK] ask PLIC for device interrupts\n");
+    binit();
+    printf("[OK] buffer cache\n");
+    iinit();
+    printf("[OK] inode table\n");
+    fileinit();
+    printf("[OK] file table\n");
+    virtio_disk_init();
+    printf("[OK] emulated hard disk\n");
+    userinit();
+    printf("[OK] first user process\n");
     __sync_synchronize();
     started = 1;
   } else {
diff --git a/kernel/memlayout.h b/kernel/memlayout.h
index abaea7d..85ecf88 100644
--- a/kernel/memlayout.h
+++ b/kernel/memlayout.h
@@ -44,7 +44,7 @@
 // the kernel expects there to be RAM
 // for use by the kernel and user pages
 // from physical address 0x80000000 to PHYSTOP.
-#define KERNBASE 0x80000000L
+#define KERNBASE 0x80200000L
 #define PHYSTOP (KERNBASE + 128 * 1024 * 1024)
 
 // map the trampoline page to the highest address,
diff --git a/shell.nix b/shell.nix
index 0a8c373..c55afee 100644
--- a/shell.nix
+++ b/shell.nix
@@ -2,5 +2,5 @@ let
   pkgs = import <nixpkgs> {};
 in
   pkgs.pkgsCross.riscv64.mkShell {
-    packages = with pkgs; [alejandra clang-tools fd gcc qemu];
+    packages = with pkgs; [alejandra cargo-binutils clang-tools fd gcc gdb qemu];
   }