diff --git a/Makefile b/Makefile
index 1424d7c..6c3df2b 100644
--- a/Makefile
+++ b/Makefile
@@ -12,7 +12,14 @@ OBJS = \
   trampoline.o \
   trap.o \
   syscall.o \
-  sysproc.o
+  sysproc.o \
+  bio.o \
+  fs.o \
+  log.o \
+  sleeplock.o \
+  file.o \
+  pipe.o \
+  ramdisk.o
 
 XXXOBJS = \
 	bio.o\
@@ -83,15 +90,15 @@ endif
 
 LDFLAGS = -z max-page-size=4096
 
-kernel: $(OBJS) entry.o kernel.ld 
+kernel: $(OBJS) entry.o kernel.ld initcode
 	$(LD) $(LDFLAGS) -T kernel.ld -o kernel entry.o $(OBJS) 
 	$(OBJDUMP) -S kernel > kernel.asm
 	$(OBJDUMP) -t kernel | sed '1,/SYMBOL TABLE/d; s/ .* / /; /^$$/d' > kernel.sym
 
 initcode: initcode.S
 	$(CC) $(CFLAGS) -nostdinc -I. -c initcode.S
-	#$(LD) $(LDFLAGS) -N -e start -Ttext 0 -o initcode.out initcode.o
-	#$(OBJCOPY) -S -O binary initcode.out initcode
+	$(LD) $(LDFLAGS) -N -e start -Ttext 0 -o initcode.out initcode.o
+	$(OBJCOPY) -S -O binary initcode.out initcode
 	$(OBJDUMP) -S initcode.o > initcode.asm
 
 tags: $(OBJS) entryother.S _init
@@ -107,6 +114,9 @@ _%: %.o $(ULIB)
 	$(OBJDUMP) -S $@ > $*.asm
 	$(OBJDUMP) -t $@ | sed '1,/SYMBOL TABLE/d; s/ .* / /; /^$$/d' > $*.sym
 
+usys.S : usys.pl
+	perl ./usys.pl > usys.S
+
 _forktest: forktest.o $(ULIB)
 	# forktest has less library code linked in - needs to be small
 	# in order to be able to max out the proc table.
@@ -171,7 +181,7 @@ ifndef CPUS
 CPUS := 1
 endif
 QEMUOPTS = -machine virt -kernel kernel -m 3G -smp $(CPUS) -nographic
-#QEMUOPTS += -initrd fs.img
+QEMUOPTS += -initrd fs.img
 
 qemu: kernel
 	$(QEMU) $(QEMUOPTS)
diff --git a/bio.c b/bio.c
index a45ff3e..90f9af9 100644
--- a/bio.c
+++ b/bio.c
@@ -19,10 +19,11 @@
 //     and needs to be written to disk.
 
 #include "types.h"
-#include "defs.h"
 #include "param.h"
 #include "spinlock.h"
 #include "sleeplock.h"
+#include "riscv.h"
+#include "defs.h"
 #include "fs.h"
 #include "buf.h"
 
@@ -100,7 +101,7 @@ bread(uint dev, uint blockno)
 
   b = bget(dev, blockno);
   if((b->flags & B_VALID) == 0) {
-    iderw(b);
+    ramdiskrw(b);
   }
   return b;
 }
@@ -112,7 +113,7 @@ bwrite(struct buf *b)
   if(!holdingsleep(&b->lock))
     panic("bwrite");
   b->flags |= B_DIRTY;
-  iderw(b);
+  ramdiskrw(b);
 }
 
 // Release a locked buffer.
diff --git a/defs.h b/defs.h
index d86e495..efffc33 100644
--- a/defs.h
+++ b/defs.h
@@ -54,10 +54,10 @@ int             readi(struct inode*, char*, uint, uint);
 void            stati(struct inode*, struct stat*);
 int             writei(struct inode*, char*, uint, uint);
 
-// ide.c
-void            ideinit(void);
-void            ideintr(void);
-void            iderw(struct buf*);
+// ramdisk.c
+void            ramdiskinit(void);
+void            ramdiskintr(void);
+void            ramdiskrw(struct buf*);
 
 // ioapic.c
 void            ioapicenable(int irq, int cpu);
diff --git a/file.c b/file.c
index 24b32c2..6d3ffb3 100644
--- a/file.c
+++ b/file.c
@@ -3,6 +3,7 @@
 //
 
 #include "types.h"
+#include "riscv.h"
 #include "defs.h"
 #include "param.h"
 #include "fs.h"
diff --git a/fs.c b/fs.c
index feb59fe..ae96567 100644
--- a/fs.c
+++ b/fs.c
@@ -10,10 +10,10 @@
 // are in sysfile.c.
 
 #include "types.h"
+#include "riscv.h"
 #include "defs.h"
 #include "param.h"
 #include "stat.h"
-#include "mmu.h"
 #include "proc.h"
 #include "spinlock.h"
 #include "sleeplock.h"
@@ -180,7 +180,7 @@ iinit(int dev)
   }
 
   readsb(dev, &sb);
-  cprintf("sb: size %d nblocks %d ninodes %d nlog %d logstart %d\
+  printf("sb: size %d nblocks %d ninodes %d nlog %d logstart %d\
  inodestart %d bmap start %d\n", sb.size, sb.nblocks,
           sb.ninodes, sb.nlog, sb.logstart, sb.inodestart,
           sb.bmapstart);
diff --git a/ide.c b/ide.c
deleted file mode 100644
index b4c0b1f..0000000
--- a/ide.c
+++ /dev/null
@@ -1,168 +0,0 @@
-// Simple PIO-based (non-DMA) IDE driver code.
-
-#include "types.h"
-#include "defs.h"
-#include "param.h"
-#include "memlayout.h"
-#include "mmu.h"
-#include "proc.h"
-#include "x86.h"
-#include "traps.h"
-#include "spinlock.h"
-#include "sleeplock.h"
-#include "fs.h"
-#include "buf.h"
-
-#define SECTOR_SIZE   512
-#define IDE_BSY       0x80
-#define IDE_DRDY      0x40
-#define IDE_DF        0x20
-#define IDE_ERR       0x01
-
-#define IDE_CMD_READ  0x20
-#define IDE_CMD_WRITE 0x30
-#define IDE_CMD_RDMUL 0xc4
-#define IDE_CMD_WRMUL 0xc5
-
-// idequeue points to the buf now being read/written to the disk.
-// idequeue->qnext points to the next buf to be processed.
-// You must hold idelock while manipulating queue.
-
-static struct spinlock idelock;
-static struct buf *idequeue;
-
-static int havedisk1;
-static void idestart(struct buf*);
-
-// Wait for IDE disk to become ready.
-static int
-idewait(int checkerr)
-{
-  int r;
-
-  while(((r = inb(0x1f7)) & (IDE_BSY|IDE_DRDY)) != IDE_DRDY)
-    ;
-  if(checkerr && (r & (IDE_DF|IDE_ERR)) != 0)
-    return -1;
-  return 0;
-}
-
-void
-ideinit(void)
-{
-  int i;
-
-  initlock(&idelock, "ide");
-  ioapicenable(IRQ_IDE, ncpu - 1);
-  idewait(0);
-
-  // Check if disk 1 is present
-  outb(0x1f6, 0xe0 | (1<<4));
-  for(i=0; i<1000; i++){
-    if(inb(0x1f7) != 0){
-      havedisk1 = 1;
-      break;
-    }
-  }
-
-  // Switch back to disk 0.
-  outb(0x1f6, 0xe0 | (0<<4));
-}
-
-// Start the request for b.  Caller must hold idelock.
-static void
-idestart(struct buf *b)
-{
-  if(b == 0)
-    panic("idestart");
-  if(b->blockno >= FSSIZE)
-    panic("incorrect blockno");
-  int sector_per_block =  BSIZE/SECTOR_SIZE;
-  int sector = b->blockno * sector_per_block;
-  int read_cmd = (sector_per_block == 1) ? IDE_CMD_READ :  IDE_CMD_RDMUL;
-  int write_cmd = (sector_per_block == 1) ? IDE_CMD_WRITE : IDE_CMD_WRMUL;
-
-  if (sector_per_block > 7) panic("idestart");
-
-  idewait(0);
-  outb(0x3f6, 0);  // generate interrupt
-  outb(0x1f2, sector_per_block);  // number of sectors
-  outb(0x1f3, sector & 0xff);
-  outb(0x1f4, (sector >> 8) & 0xff);
-  outb(0x1f5, (sector >> 16) & 0xff);
-  outb(0x1f6, 0xe0 | ((b->dev&1)<<4) | ((sector>>24)&0x0f));
-  if(b->flags & B_DIRTY){
-    outb(0x1f7, write_cmd);
-    outsl(0x1f0, b->data, BSIZE/4);
-  } else {
-    outb(0x1f7, read_cmd);
-  }
-}
-
-// Interrupt handler.
-void
-ideintr(void)
-{
-  struct buf *b;
-
-  // First queued buffer is the active request.
-  acquire(&idelock);
-
-  if((b = idequeue) == 0){
-    release(&idelock);
-    return;
-  }
-  idequeue = b->qnext;
-
-  // Read data if needed.
-  if(!(b->flags & B_DIRTY) && idewait(1) >= 0)
-    insl(0x1f0, b->data, BSIZE/4);
-
-  // Wake process waiting for this buf.
-  b->flags |= B_VALID;
-  b->flags &= ~B_DIRTY;
-  wakeup(b);
-
-  // Start disk on next buf in queue.
-  if(idequeue != 0)
-    idestart(idequeue);
-
-  release(&idelock);
-}
-
-//PAGEBREAK!
-// Sync buf with disk.
-// If B_DIRTY is set, write buf to disk, clear B_DIRTY, set B_VALID.
-// Else if B_VALID is not set, read buf from disk, set B_VALID.
-void
-iderw(struct buf *b)
-{
-  struct buf **pp;
-
-  if(!holdingsleep(&b->lock))
-    panic("iderw: buf not locked");
-  if((b->flags & (B_VALID|B_DIRTY)) == B_VALID)
-    panic("iderw: nothing to do");
-  if(b->dev != 0 && !havedisk1)
-    panic("iderw: ide disk 1 not present");
-
-  acquire(&idelock);  //DOC:acquire-lock
-
-  // Append b to idequeue.
-  b->qnext = 0;
-  for(pp=&idequeue; *pp; pp=&(*pp)->qnext)  //DOC:insert-queue
-    ;
-  *pp = b;
-
-  // Start disk if necessary.
-  if(idequeue == b)
-    idestart(b);
-
-  // Wait for request to finish.
-  while((b->flags & (B_VALID|B_DIRTY)) != B_VALID){
-    sleep(b, &idelock);
-  }
-
-
-  release(&idelock);
-}
diff --git a/kalloc.c b/kalloc.c
index c943e5e..cfbbae4 100644
--- a/kalloc.c
+++ b/kalloc.c
@@ -27,6 +27,8 @@ void
 kinit()
 {
   initlock(&kmem.lock, "kmem");
+  if(PHYSTOP > RAMDISK)
+    panic("kinit");
   freerange(end, (void*)PHYSTOP);
 }
 
diff --git a/log.c b/log.c
index a64c0f6..c8f7e62 100644
--- a/log.c
+++ b/log.c
@@ -1,4 +1,5 @@
 #include "types.h"
+#include "riscv.h"
 #include "defs.h"
 #include "param.h"
 #include "spinlock.h"
diff --git a/main.c b/main.c
index 04e822a..d4a30f0 100644
--- a/main.c
+++ b/main.c
@@ -17,11 +17,9 @@ main()
   kvminit();       // kernel page table
   procinit();      // process table
   trapinit();      // trap vectors
-#if 0
   binit();         // buffer cache
   fileinit();      // file table
-  ideinit();       // disk
-#endif
+  ramdiskinit();   // disk
   userinit();      // first user process
 
   scheduler();        
diff --git a/memlayout.h b/memlayout.h
index 798621e..9bc9c5d 100644
--- a/memlayout.h
+++ b/memlayout.h
@@ -4,6 +4,8 @@
 // 00001000 -- boot ROM, provided by qemu
 // 10000000 -- uart0 registers
 // 80000000 -- boot ROM jumps here in machine mode
+//             -kernel loads the kernel here
+// 88000000 -- -initrd fs.img ramdisk image.
 // unused RAM after 80000000.
 
 // the kernel uses physical memory thus:
@@ -14,6 +16,8 @@
 // registers start here in physical memory.
 #define UART0 0x10000000L
 
+#define RAMDISK 0x88000000
+
 // the kernel expects there to be RAM
 // for use by the kernel and user pages
 // from physical address 0x80000000 to PHYSTOP.
diff --git a/pipe.c b/pipe.c
index e9abe7f..1274a3a 100644
--- a/pipe.c
+++ b/pipe.c
@@ -1,7 +1,7 @@
 #include "types.h"
+#include "riscv.h"
 #include "defs.h"
 #include "param.h"
-#include "mmu.h"
 #include "proc.h"
 #include "fs.h"
 #include "spinlock.h"
diff --git a/proc.c b/proc.c
index e574db0..a099e98 100644
--- a/proc.c
+++ b/proc.c
@@ -116,16 +116,13 @@ found:
   return p;
 }
 
-// XXX hack because I don't know how to incorporate initcode
-// into the kernel binary. just the exec system call, no arguments.
-// manually copied from initcode.asm.
+// a user program that calls exec("/init")
+// od -t xC initcode
 unsigned char initcode[] = {
-  0x85, 0x48,             // li a7, 1 -- SYS_fork
-  0x73, 0x00, 0x00, 0x00, // ecall
-  0x8d, 0x48,             // li a7, 3 -- SYS_wait
-  0x73, 0x00, 0x00, 0x00, // ecall
-  0x89, 0x48,             // li a7, 2 -- SYS_exit
-  0x73, 0x00, 0x00, 0x00, // ecall
+  0x17, 0x05, 0x00, 0x00, 0x13, 0x05, 0x05, 0x02, 0x97, 0x05, 0x00, 0x00, 0x93, 0x85, 0x05, 0x02,
+  0x9d, 0x48, 0x73, 0x00, 0x00, 0x00, 0x89, 0x48, 0x73, 0x00, 0x00, 0x00, 0xef, 0xf0, 0xbf, 0xff,
+  0x2f, 0x69, 0x6e, 0x69, 0x74, 0x00, 0x00, 0x01, 0x20, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
+  0x00, 0x00, 0x00
 };
 
 //PAGEBREAK: 32
@@ -146,8 +143,7 @@ userinit(void)
   p->tf->sp = PGSIZE;
 
   safestrcpy(p->name, "initcode", sizeof(p->name));
-  // XXX riscv
-  //p->cwd = namei("/");
+  p->cwd = namei("/");
 
   // this assignment to p->state lets other cores
   // run this process. the acquire forces the above
@@ -210,13 +206,11 @@ fork(void)
   // Cause fork to return 0 in the child.
   np->tf->a0 = 0;
 
-#if 0 // XXX riscv
   // increment reference counts on open file descriptors.
   for(i = 0; i < NOFILE; i++)
     if(p->ofile[i])
       np->ofile[i] = filedup(p->ofile[i]);
   np->cwd = idup(p->cwd);
-#endif
 
   safestrcpy(np->name, p->name, sizeof(p->name));
 
@@ -244,7 +238,6 @@ exit(void)
   if(p == initproc)
     panic("init exiting");
 
-#if 0 // XXX riscv
   // Close all open files.
   for(fd = 0; fd < NOFILE; fd++){
     if(p->ofile[fd]){
@@ -256,7 +249,6 @@ exit(void)
   begin_op();
   iput(p->cwd);
   end_op();
-#endif
   p->cwd = 0;
 
   acquire(&ptable.lock);
@@ -423,9 +415,8 @@ forkret(void)
     // of a regular process (e.g., they call sleep), and thus cannot
     // be run from main().
     first = 0;
-    // XXX riscv
-    //iinit(ROOTDEV);
-    //initlog(ROOTDEV);
+    iinit(ROOTDEV);
+    initlog(ROOTDEV);
   }
 
   usertrapret();
diff --git a/ramdisk.c b/ramdisk.c
new file mode 100644
index 0000000..9901294
--- /dev/null
+++ b/ramdisk.c
@@ -0,0 +1,45 @@
+//
+// ramdisk that uses the disk image loaded by qemu -rdinit fs.img
+//
+
+#include "types.h"
+#include "riscv.h"
+#include "defs.h"
+#include "param.h"
+#include "memlayout.h"
+#include "spinlock.h"
+#include "sleeplock.h"
+#include "fs.h"
+#include "buf.h"
+
+void
+ramdiskinit(void)
+{
+}
+
+// If B_DIRTY is set, write buf to disk, clear B_DIRTY, set B_VALID.
+// Else if B_VALID is not set, read buf from disk, set B_VALID.
+void
+ramdiskrw(struct buf *b)
+{
+  if(!holdingsleep(&b->lock))
+    panic("ramdiskrw: buf not locked");
+  if((b->flags & (B_VALID|B_DIRTY)) == B_VALID)
+    panic("ramdiskrw: nothing to do");
+
+  if(b->blockno >= FSSIZE)
+    panic("ramdiskrw: blockno too big");
+
+  uint64 diskaddr = b->blockno * BSIZE;
+  char *addr = (char *)RAMDISK + diskaddr;
+
+  if(b->flags & B_DIRTY){
+    // write
+    memmove(addr, b->data, BSIZE);
+    b->flags &= ~B_DIRTY;
+  } else {
+    // read
+    memmove(b->data, addr, BSIZE);
+    b->flags |= B_VALID;
+  }
+}
diff --git a/sleeplock.c b/sleeplock.c
index e0750ea..b490370 100644
--- a/sleeplock.c
+++ b/sleeplock.c
@@ -1,11 +1,10 @@
 // Sleeping locks
 
 #include "types.h"
+#include "riscv.h"
 #include "defs.h"
 #include "param.h"
-#include "x86.h"
 #include "memlayout.h"
-#include "mmu.h"
 #include "proc.h"
 #include "spinlock.h"
 #include "sleeplock.h"
diff --git a/trapasm.S b/trapasm.S
deleted file mode 100644
index 6b6b567..0000000
--- a/trapasm.S
+++ /dev/null
@@ -1,132 +0,0 @@
-#include "param.h"
-#include "x86.h"	
-#include "mmu.h"
-
-# the offset of cs in trapframe (i.e., tf->cs - tf)
-#define CSOFF  144
-	
-# vectors.S sends all traps here.
-.globl alltraps
-alltraps:
-  # Build trap frame.
-  push %r15
-  push %r14
-  push %r13
-  push %r12
-  push %r11
-  push %r10
-  push %r9
-  push %r8
-  push %rdi
-  push %rsi
-  push %rbp
-  push %rdx
-  push %rcx
-  push %rbx
-  push %rax
-
-  cmpw $SEG_KCODE, CSOFF(%rsp)   # compare to saved cs
-  jz 1f 
-  swapgs
-  
-1:mov  %rsp, %rdi  # frame in arg1
-  call trap
-
-# Return falls through to trapret...
-.globl trapret
-trapret:
-  cli
-  cmpw $SEG_KCODE, CSOFF(%rsp)  # compare to saved cs
-  jz 1f
-  swapgs
-
-1:pop %rax
-  pop %rbx
-  pop %rcx
-  pop %rdx
-  pop %rbp
-  pop %rsi
-  pop %rdi
-  pop %r8
-  pop %r9
-  pop %r10
-  pop %r11
-  pop %r12
-  pop %r13
-  pop %r14
-  pop %r15
-
-  add $16, %rsp  # discard trapnum and errorcode
-  iretq
-
-#PAGEBREAK!
-
-# syscall jumps here after syscall instruction
-.globl sysentry
-sysentry:  # Build syscall frame.
-  // load kernel stack address
-  swapgs
-  movq  %rax, %gs:0  // save %rax in syscallno of cpu entry
-  movq  %rsp, %gs:8  // user sp
-  movq  %gs:16, %rax  // proc entry
-  
-  movq  %ss:0(%rax), %rax // load kstack from proc
-  addq  $(KSTACKSIZE), %rax
-
-  movq  %rax, %rsp
-  movq  %gs:0, %rax  // restore rax
-
-  push %gs:8
-  push %rcx
-  push %r11	
-  push %rax	
-
-  push %rbp
-  push %rbx	
-  push %r12 
-  push %r13
-  push %r14
-  push %r15	
-
-  push %r9
-  push %r8	
-  push %r10
-  push %rdx
-  push %rsi	
-  push %rdi
-	
-  mov  %rsp, %rdi  # frame in arg1
-
-  call syscall
-  # fall through to sysexit
-	
-.globl sysexit
-sysexit:
-  # to make sure we don't get any interrupts on the user stack while in
-  # supervisor mode.  insufficient?  (see vunerability reports for sysret)
-  cli
-	
-  pop %rdi
-  pop %rsi
-  pop %rdx
-  pop %r10
-  pop %r8
-  pop %r9
-
-  pop %r15
-  pop %r14
-  pop %r13
-  pop %r12
-  pop %rbx
-  pop %rbp
-
-  pop %rax
-  pop %r11
-  pop %rcx
-
-  mov (%rsp),%rsp  # switch to the user stack
-  # there are two more values on the stack, but we don't care about them	
-  swapgs	
-
-  sysretq
-
diff --git a/ulib.c b/ulib.c
index 8e1e1a2..532fe42 100644
--- a/ulib.c
+++ b/ulib.c
@@ -2,7 +2,6 @@
 #include "stat.h"
 #include "fcntl.h"
 #include "user.h"
-#include "x86.h"
 
 char*
 strcpy(char *s, const char *t)
@@ -36,7 +35,11 @@ strlen(const char *s)
 void*
 memset(void *dst, int c, uint n)
 {
-  stosb(dst, c, n);
+  char *cdst = (char *) dst;
+  int i;
+  for(i = 0; i < n; i++){
+    cdst[i] = c;
+  }
   return dst;
 }
 
diff --git a/usertests.c b/usertests.c
index 3cd8b34..292319e 100644
--- a/usertests.c
+++ b/usertests.c
@@ -5,7 +5,6 @@
 #include "fs.h"
 #include "fcntl.h"
 #include "syscall.h"
-#include "traps.h"
 #include "memlayout.h"
 
 char buf[8192];
@@ -1713,35 +1712,6 @@ fsfull()
   printf(1, "fsfull test finished\n");
 }
 
-void
-uio()
-{
-  #define RTC_ADDR 0x70
-  #define RTC_DATA 0x71
-
-  ushort port = 0;
-  uchar val = 0;
-  int pid;
-
-  printf(1, "uio test\n");
-  pid = fork();
-  if(pid == 0){
-    port = RTC_ADDR;
-    val = 0x09;  /* year */
-    /* http://wiki.osdev.org/Inline_Assembly/Examples */
-    asm volatile("outb %0,%1"::"a"(val), "d" (port));
-    port = RTC_DATA;
-    asm volatile("inb %1,%0" : "=a" (val) : "d" (port));
-    printf(1, "uio: uio succeeded; test FAILED\n");
-    exit();
-  } else if(pid < 0){
-    printf (1, "fork failed\n");
-    exit();
-  }
-  wait();
-  printf(1, "uio test done\n");
-}
-
 void argptest()
 {
   int fd;
@@ -1813,8 +1783,6 @@ main(int argc, char *argv[])
   forktest();
   bigdir(); // slow
 
-  uio();
-
   exectest();
 
   exit();
diff --git a/usys.S b/usys.S
deleted file mode 100644
index 69935e7..0000000
--- a/usys.S
+++ /dev/null
@@ -1,31 +0,0 @@
-#include "syscall.h"
-#include "traps.h"
-
-#define SYSCALL(name) \
-  .globl name; \
-  name: \
-    mov $SYS_ ## name, %rax; \
-    syscall; \
-    ret
-
-SYSCALL(fork)
-SYSCALL(exit)
-SYSCALL(wait)
-SYSCALL(pipe)
-SYSCALL(read)
-SYSCALL(write)
-SYSCALL(close)
-SYSCALL(kill)
-SYSCALL(exec)
-SYSCALL(open)
-SYSCALL(mknod)
-SYSCALL(unlink)
-SYSCALL(fstat)
-SYSCALL(link)
-SYSCALL(mkdir)
-SYSCALL(chdir)
-SYSCALL(dup)
-SYSCALL(getpid)
-SYSCALL(sbrk)
-SYSCALL(sleep)
-SYSCALL(uptime)
diff --git a/usys.pl b/usys.pl
new file mode 100755
index 0000000..f8d47d5
--- /dev/null
+++ b/usys.pl
@@ -0,0 +1,38 @@
+#!/usr/bin/perl -w
+
+# Generate usys.S, the stubs for syscalls.
+
+print "# generated by usys.pl - do not edit\n";
+
+print "#include \"syscall.h\"\n";
+
+sub entry {
+    my $name = shift;
+    print ".global $name\n";
+    print "${name}:\n";
+    print " li a7, SYS_${name}\n";
+    print " ecall\n";
+    print " ret\n";
+}
+	
+entry("fork");
+entry("exit");
+entry("wait");
+entry("pipe");
+entry("read");
+entry("write");
+entry("close");
+entry("kill");
+entry("exec");
+entry("open");
+entry("mknod");
+entry("unlink");
+entry("fstat");
+entry("link");
+entry("mkdir");
+entry("chdir");
+entry("dup");
+entry("getpid");
+entry("sbrk");
+entry("sleep");
+entry("uptime");
diff --git a/vm.c b/vm.c
index 8c2ccb3..a0d6569 100644
--- a/vm.c
+++ b/vm.c
@@ -4,6 +4,7 @@
 #include "elf.h"
 #include "riscv.h"
 #include "defs.h"
+#include "fs.h"
 
 /*
  * the kernel's page table.
@@ -37,6 +38,10 @@ kvminit()
   mappages(kernel_pagetable, (uint64)etext, PHYSTOP-(uint64)etext,
            (uint64)etext, PTE_R | PTE_W);
 
+  // map the qemu -initrd fs.img ramdisk
+  mappages(kernel_pagetable, RAMDISK, FSSIZE * BSIZE,
+           RAMDISK, PTE_R | PTE_W);
+
   // map the trampoline for trap entry/exit to
   // the highest virtual address in the kernel.
   mappages(kernel_pagetable, TRAMPOLINE, PGSIZE,