diff --git a/commands/iorw.c b/commands/iorw.c
new file mode 100644
index 000000000..5e685a264
--- /dev/null
+++ b/commands/iorw.c
@@ -0,0 +1,146 @@
+/* memrw.c - command to read / write physical memory  */
+/*
+ *  GRUB  --  GRand Unified Bootloader
+ *  Copyright (C) 2009  Free Software Foundation, Inc.
+ *
+ *  GRUB is free software: you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation, either version 3 of the License, or
+ *  (at your option) any later version.
+ *
+ *  GRUB is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with GRUB.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <grub/dl.h>
+#include <grub/misc.h>
+#include <grub/extcmd.h>
+#include <grub/env.h>
+#include <grub/cpu/io.h>
+
+static grub_extcmd_t cmd_read_byte, cmd_read_word, cmd_read_dword;
+static grub_command_t cmd_write_byte, cmd_write_word, cmd_write_dword;
+
+static const struct grub_arg_option options[] =
+  {
+    {0, 'v', 0, "Save read value into variable VARNAME.",
+     "VARNAME", ARG_TYPE_STRING},
+    {0, 0, 0, 0, 0, 0}
+  };
+
+
+static grub_err_t
+grub_cmd_read (grub_extcmd_t cmd, int argc, char **argv)
+{
+  grub_target_addr_t addr;
+  grub_uint32_t value = 0;
+  char buf[sizeof ("XXXXXXXX")];
+
+  if (argc != 1)
+    return grub_error (GRUB_ERR_BAD_ARGUMENT, "Invalid number of arguments");
+
+  addr = grub_strtoul (argv[0], 0, 0);
+  switch (cmd->cmd->name[sizeof ("grub_in") - 1])
+    {
+    case 'l':
+      value = grub_inl (addr);
+      break;
+
+    case 'w':
+      value = grub_inw (addr);
+      break;
+
+    case 'b':
+      value = grub_inb (addr);
+      break;
+    }
+
+  if (cmd->state[0].set)
+    {
+      grub_sprintf (buf, "%x", value);
+      grub_env_set (cmd->state[0].arg, buf);
+    }
+  else
+    grub_printf ("0x%x\n", value);
+
+  return 0;
+}
+
+static grub_err_t
+grub_cmd_write (grub_command_t cmd, int argc, char **argv)
+{
+  grub_target_addr_t addr;
+  grub_uint32_t value;
+  grub_uint32_t mask = 0xffffffff;
+
+  if (argc != 2 && argc != 3)
+    return grub_error (GRUB_ERR_BAD_ARGUMENT, "Invalid number of arguments");
+
+  addr = grub_strtoul (argv[0], 0, 0);
+  value = grub_strtoul (argv[1], 0, 0);
+  if (argc == 3)
+    mask = grub_strtoul (argv[2], 0, 0);
+  value &= mask;
+  switch (cmd->name[sizeof ("grub_out") - 1])
+    {
+    case 'l':
+      if (mask != 0xffffffff)
+	grub_outl ((grub_inl (addr) & ~mask) | value, addr);
+      else
+	grub_outl (value, addr);
+      break;
+
+    case 'w':
+      if ((mask & 0xffff) != 0xffff)
+	grub_outw ((grub_inw (addr) & ~mask) | value, addr);
+      else
+	grub_outw (value, addr);
+      break;
+
+    case 'b':
+      if ((mask & 0xff) != 0xff)
+	grub_outb ((grub_inb (addr) & ~mask) | value, addr);
+      else
+	grub_outb (value, addr);
+      break;
+    }
+
+  return 0;
+}
+
+GRUB_MOD_INIT(memrw)
+{
+  cmd_read_byte =
+    grub_register_extcmd ("grub_inb", grub_cmd_read, GRUB_COMMAND_FLAG_BOTH,
+			  "grub_inb PORT", "Read byte from PORT.", options);
+  cmd_read_word =
+    grub_register_extcmd ("grub_inw", grub_cmd_read, GRUB_COMMAND_FLAG_BOTH,
+			  "grub_inw PORT", "Read word from PORT.", options);
+  cmd_read_dword =
+    grub_register_extcmd ("grub_inl", grub_cmd_read, GRUB_COMMAND_FLAG_BOTH,
+			  "grub_inl PORT", "Read dword from PORT.", options);
+  cmd_write_byte =
+    grub_register_command ("grub_outb", grub_cmd_write,
+			   "grub_outb PORT VALUE [MASK]", "Write byte VALUE to PORT.");
+  cmd_write_word =
+    grub_register_command ("grub_outw", grub_cmd_write,
+			   "grub_outw PORT VALUE [MASK]", "Write word VALUE to PORT.");
+  cmd_write_dword =
+    grub_register_command ("grub_outl", grub_cmd_write,
+			   "grub_outl ADDR VALUE [MASK]", "Write dword VALUE to PORT.");
+}
+
+GRUB_MOD_FINI(memrw)
+{
+  grub_unregister_extcmd (cmd_read_byte);
+  grub_unregister_extcmd (cmd_read_word);
+  grub_unregister_extcmd (cmd_read_dword);
+  grub_unregister_command (cmd_write_byte);
+  grub_unregister_command (cmd_write_word);
+  grub_unregister_command (cmd_write_dword);
+}
diff --git a/conf/i386.rmk b/conf/i386.rmk
index c3f036d0f..45d2c0818 100644
--- a/conf/i386.rmk
+++ b/conf/i386.rmk
@@ -25,3 +25,9 @@ pkglib_MODULES += ata.mod
 ata_mod_SOURCES = disk/ata.c
 ata_mod_CFLAGS = $(COMMON_CFLAGS)
 ata_mod_LDFLAGS = $(COMMON_LDFLAGS)
+
+# For iorw.mod.
+pkglib_MODULES += iorw.mod
+iorw_mod_SOURCES = commands/iorw.c
+iorw_mod_CFLAGS = $(COMMON_CFLAGS)
+iorw_mod_LDFLAGS = $(COMMON_LDFLAGS)