diff --git a/libc/kernel/arch-arm/asm/param.h b/libc/kernel/arch-arm/asm/param.h
index 23d45c7..6814fe3 100644
--- a/libc/kernel/arch-arm/asm/param.h
+++ b/libc/kernel/arch-arm/asm/param.h
@@ -20,7 +20,6 @@
 #define NOGROUP (-1)
 #endif
 
-#define MAXHOSTNAMELEN 64
 
 #endif
 
diff --git a/libc/kernel/arch-x86/asm/param.h b/libc/kernel/arch-x86/asm/param.h
index 0825173..3fafd55 100644
--- a/libc/kernel/arch-x86/asm/param.h
+++ b/libc/kernel/arch-x86/asm/param.h
@@ -22,6 +22,5 @@
 #define NOGROUP (-1)
 #endif
 
-#define MAXHOSTNAMELEN 64  
 
 #endif
diff --git a/libc/kernel/common/linux/dm-ioctl.h b/libc/kernel/common/linux/dm-ioctl.h
new file mode 100644
index 0000000..ead7744
--- /dev/null
+++ b/libc/kernel/common/linux/dm-ioctl.h
@@ -0,0 +1,146 @@
+/****************************************************************************
+ ****************************************************************************
+ ***
+ ***   This header was automatically generated from a Linux kernel header
+ ***   of the same name, to make information necessary for userspace to
+ ***   call into the kernel available to libc.  It contains only constants,
+ ***   structures, and macros generated from the original header, and thus,
+ ***   contains no copyrightable information.
+ ***
+ ****************************************************************************
+ ****************************************************************************/
+#ifndef _LINUX_DM_IOCTL_V4_H
+#define _LINUX_DM_IOCTL_V4_H
+
+#include <linux/types.h>
+
+#define DM_DIR "mapper"  
+#define DM_MAX_TYPE_NAME 16
+#define DM_NAME_LEN 128
+#define DM_UUID_LEN 129
+
+struct dm_ioctl {
+
+ uint32_t version[3];
+ uint32_t data_size;
+
+ uint32_t data_start;
+
+ uint32_t target_count;
+ int32_t open_count;
+ uint32_t flags;
+ uint32_t event_nr;
+ uint32_t padding;
+
+ uint64_t dev;
+
+ char name[DM_NAME_LEN];
+ char uuid[DM_UUID_LEN];
+ char data[7];
+};
+
+struct dm_target_spec {
+ uint64_t sector_start;
+ uint64_t length;
+ int32_t status;
+
+ uint32_t next;
+
+ char target_type[DM_MAX_TYPE_NAME];
+
+};
+
+struct dm_target_deps {
+ uint32_t count;
+ uint32_t padding;
+ uint64_t dev[0];
+};
+
+struct dm_name_list {
+ uint64_t dev;
+ uint32_t next;
+ char name[0];
+};
+
+struct dm_target_versions {
+ uint32_t next;
+ uint32_t version[3];
+
+ char name[0];
+};
+
+struct dm_target_msg {
+ uint64_t sector;
+
+ char message[0];
+};
+
+enum {
+
+ DM_VERSION_CMD = 0,
+ DM_REMOVE_ALL_CMD,
+ DM_LIST_DEVICES_CMD,
+
+ DM_DEV_CREATE_CMD,
+ DM_DEV_REMOVE_CMD,
+ DM_DEV_RENAME_CMD,
+ DM_DEV_SUSPEND_CMD,
+ DM_DEV_STATUS_CMD,
+ DM_DEV_WAIT_CMD,
+
+ DM_TABLE_LOAD_CMD,
+ DM_TABLE_CLEAR_CMD,
+ DM_TABLE_DEPS_CMD,
+ DM_TABLE_STATUS_CMD,
+
+ DM_LIST_VERSIONS_CMD,
+ DM_TARGET_MSG_CMD,
+ DM_DEV_SET_GEOMETRY_CMD
+};
+
+#define DM_IOCTL 0xfd
+
+#define DM_VERSION _IOWR(DM_IOCTL, DM_VERSION_CMD, struct dm_ioctl)
+#define DM_REMOVE_ALL _IOWR(DM_IOCTL, DM_REMOVE_ALL_CMD, struct dm_ioctl)
+#define DM_LIST_DEVICES _IOWR(DM_IOCTL, DM_LIST_DEVICES_CMD, struct dm_ioctl)
+
+#define DM_DEV_CREATE _IOWR(DM_IOCTL, DM_DEV_CREATE_CMD, struct dm_ioctl)
+#define DM_DEV_REMOVE _IOWR(DM_IOCTL, DM_DEV_REMOVE_CMD, struct dm_ioctl)
+#define DM_DEV_RENAME _IOWR(DM_IOCTL, DM_DEV_RENAME_CMD, struct dm_ioctl)
+#define DM_DEV_SUSPEND _IOWR(DM_IOCTL, DM_DEV_SUSPEND_CMD, struct dm_ioctl)
+#define DM_DEV_STATUS _IOWR(DM_IOCTL, DM_DEV_STATUS_CMD, struct dm_ioctl)
+#define DM_DEV_WAIT _IOWR(DM_IOCTL, DM_DEV_WAIT_CMD, struct dm_ioctl)
+
+#define DM_TABLE_LOAD _IOWR(DM_IOCTL, DM_TABLE_LOAD_CMD, struct dm_ioctl)
+#define DM_TABLE_CLEAR _IOWR(DM_IOCTL, DM_TABLE_CLEAR_CMD, struct dm_ioctl)
+#define DM_TABLE_DEPS _IOWR(DM_IOCTL, DM_TABLE_DEPS_CMD, struct dm_ioctl)
+#define DM_TABLE_STATUS _IOWR(DM_IOCTL, DM_TABLE_STATUS_CMD, struct dm_ioctl)
+
+#define DM_LIST_VERSIONS _IOWR(DM_IOCTL, DM_LIST_VERSIONS_CMD, struct dm_ioctl)
+
+#define DM_TARGET_MSG _IOWR(DM_IOCTL, DM_TARGET_MSG_CMD, struct dm_ioctl)
+#define DM_DEV_SET_GEOMETRY _IOWR(DM_IOCTL, DM_DEV_SET_GEOMETRY_CMD, struct dm_ioctl)
+
+#define DM_VERSION_MAJOR 4
+#define DM_VERSION_MINOR 14
+#define DM_VERSION_PATCHLEVEL 0
+#define DM_VERSION_EXTRA "-ioctl (2008-04-23)"
+
+#define DM_READONLY_FLAG (1 << 0)  
+#define DM_SUSPEND_FLAG (1 << 1)  
+#define DM_PERSISTENT_DEV_FLAG (1 << 3)  
+
+#define DM_STATUS_TABLE_FLAG (1 << 4)  
+
+#define DM_ACTIVE_PRESENT_FLAG (1 << 5)  
+#define DM_INACTIVE_PRESENT_FLAG (1 << 6)  
+
+#define DM_BUFFER_FULL_FLAG (1 << 8)  
+
+#define DM_SKIP_BDGET_FLAG (1 << 9)  
+
+#define DM_SKIP_LOCKFS_FLAG (1 << 10)  
+
+#define DM_NOFLUSH_FLAG (1 << 11)  
+
+#endif
diff --git a/libc/kernel/common/linux/keychord.h b/libc/kernel/common/linux/keychord.h
new file mode 100644
index 0000000..9148431
--- /dev/null
+++ b/libc/kernel/common/linux/keychord.h
@@ -0,0 +1,30 @@
+/****************************************************************************
+ ****************************************************************************
+ ***
+ ***   This header was automatically generated from a Linux kernel header
+ ***   of the same name, to make information necessary for userspace to
+ ***   call into the kernel available to libc.  It contains only constants,
+ ***   structures, and macros generated from the original header, and thus,
+ ***   contains no copyrightable information.
+ ***
+ ****************************************************************************
+ ****************************************************************************/
+#ifndef __LINUX_KEYCHORD_H_
+#define __LINUX_KEYCHORD_H_
+
+#include <linux/input.h>
+
+#define KEYCHORD_VERSION 1
+
+struct input_keychord {
+
+ __u16 version;
+
+ __u16 id;
+
+ __u16 count;
+
+ __u16 keycodes[];
+};
+
+#endif
diff --git a/libc/kernel/common/linux/msm_audio.h b/libc/kernel/common/linux/msm_audio.h
new file mode 100644
index 0000000..58dc6f3
--- /dev/null
+++ b/libc/kernel/common/linux/msm_audio.h
@@ -0,0 +1,81 @@
+/****************************************************************************
+ ****************************************************************************
+ ***
+ ***   This header was automatically generated from a Linux kernel header
+ ***   of the same name, to make information necessary for userspace to
+ ***   call into the kernel available to libc.  It contains only constants,
+ ***   structures, and macros generated from the original header, and thus,
+ ***   contains no copyrightable information.
+ ***
+ ****************************************************************************
+ ****************************************************************************/
+#ifndef __LINUX_MSM_AUDIO_H
+#define __LINUX_MSM_AUDIO_H
+
+#include <linux/types.h>
+#include <linux/ioctl.h>
+#include <asm/sizes.h>
+
+#define AUDIO_IOCTL_MAGIC 'a'
+
+#define AUDIO_START _IOW(AUDIO_IOCTL_MAGIC, 0, unsigned)
+#define AUDIO_STOP _IOW(AUDIO_IOCTL_MAGIC, 1, unsigned)
+#define AUDIO_FLUSH _IOW(AUDIO_IOCTL_MAGIC, 2, unsigned)
+#define AUDIO_GET_CONFIG _IOR(AUDIO_IOCTL_MAGIC, 3, unsigned)
+#define AUDIO_SET_CONFIG _IOW(AUDIO_IOCTL_MAGIC, 4, unsigned)
+#define AUDIO_GET_STATS _IOR(AUDIO_IOCTL_MAGIC, 5, unsigned)
+#define AUDIO_ENABLE_AUDPP _IOW(AUDIO_IOCTL_MAGIC, 6, unsigned)
+#define AUDIO_SET_ADRC _IOW(AUDIO_IOCTL_MAGIC, 7, unsigned)
+#define AUDIO_SET_EQ _IOW(AUDIO_IOCTL_MAGIC, 8, unsigned)
+#define AUDIO_SET_RX_IIR _IOW(AUDIO_IOCTL_MAGIC, 9, unsigned)
+#define AUDIO_SET_VOLUME _IOW(AUDIO_IOCTL_MAGIC, 10, unsigned)
+
+struct msm_audio_config {
+ uint32_t buffer_size;
+ uint32_t buffer_count;
+ uint32_t channel_count;
+ uint32_t sample_rate;
+ uint32_t type;
+ uint32_t unused[3];
+};
+
+struct msm_audio_stats {
+ uint32_t byte_count;
+ uint32_t sample_count;
+ uint32_t unused[2];
+};
+
+#define SND_IOCTL_MAGIC 's'
+
+#define SND_MUTE_UNMUTED 0
+#define SND_MUTE_MUTED 1
+
+struct msm_snd_device_config {
+ uint32_t device;
+ uint32_t ear_mute;
+ uint32_t mic_mute;
+};
+
+#define SND_SET_DEVICE _IOW(SND_IOCTL_MAGIC, 2, struct msm_device_config *)
+
+#define SND_METHOD_VOICE 0
+
+struct msm_snd_volume_config {
+ uint32_t device;
+ uint32_t method;
+ uint32_t volume;
+};
+
+#define SND_SET_VOLUME _IOW(SND_IOCTL_MAGIC, 3, struct msm_snd_volume_config *)
+
+#define SND_GET_NUM_ENDPOINTS _IOR(SND_IOCTL_MAGIC, 4, unsigned *)
+
+struct msm_snd_endpoint {
+ int id;
+ char name[64];
+};
+
+#define SND_GET_ENDPOINT _IOWR(SND_IOCTL_MAGIC, 5, struct msm_snd_endpoint *)
+
+#endif
+
diff --git a/libc/kernel/tools/clean_header.py b/libc/kernel/tools/clean_header.py
index bed9926..de4bf85 100755
--- a/libc/kernel/tools/clean_header.py
+++ b/libc/kernel/tools/clean_header.py
@@ -69,6 +69,7 @@
     list.removeVarsAndFuncs( statics )
     list.removeComments()
     list.removeEmptyLines()
+    list.removeMacroDefines( kernel_ignored_macros )
     list.insertDisclaimer( kernel.kernel_disclaimer )
 
     out = StringOutput()
diff --git a/libc/kernel/tools/cpp.py b/libc/kernel/tools/cpp.py
index 54ebaf4..4b4bd38 100644
--- a/libc/kernel/tools/cpp.py
+++ b/libc/kernel/tools/cpp.py
@@ -1571,6 +1571,13 @@
         """returns True iff this is a conditional directive block"""
         return self.directive in ["if","ifdef","ifndef","else","elif","endif"]
 
+    def isDefine(self):
+        """returns the macro name in a #define directive, or None otherwise"""
+        if self.directive != "define":
+            return None
+
+        return self.tokens[0].value
+
     def isIf(self):
         """returns True iff this is an #if-like directive block"""
         return self.directive in ["if","ifdef","ifndef","elif"]
@@ -1678,6 +1685,10 @@
             if b.isIf():
                 b.expr.optimize(macros)
 
+    def removeMacroDefines(self,macros):
+        """remove known macro definitions from a BlockList"""
+        self.blocks = remove_macro_defines(self.blocks,macros)
+
     def removePrefixed(self,prefix,names):
         for b in self.blocks:
             if b.isIf():
@@ -1994,6 +2005,16 @@
 #####################################################################################
 #####################################################################################
 
+def  remove_macro_defines( blocks, excludedMacros=set() ):
+    """remove macro definitions like #define <macroName>  ...."""
+    result = []
+    for b in blocks:
+        macroName = b.isDefine()
+        if macroName == None or not macroName in excludedMacros:
+            result.append(b)
+
+    return result
+
 def  find_matching_endif( blocks, i ):
     n     = len(blocks)
     depth = 1
diff --git a/libc/kernel/tools/defaults.py b/libc/kernel/tools/defaults.py
index da78b87..aad0092 100644
--- a/libc/kernel/tools/defaults.py
+++ b/libc/kernel/tools/defaults.py
@@ -73,6 +73,17 @@
         "x86" : kernel_known_x86_statics
     }
 
+# this is a list of macros which we want to specifically exclude from
+# the generated files.
+#
+kernel_ignored_macros = set(
+        [ "MAXHOSTNAMELEN",  # for some reason, Linux defines it to 64
+                             # while most of the BSD code expects this to be 256
+                             # so ignore the kernel-provided definition and
+                             # define it in the Bionic headers instead
+        ]
+    )
+
 # this is the standard disclaimer
 #
 kernel_disclaimer = """\