Hacking the Netgear wgt634u

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Revision as of 20:20, 4 May 2005 by 82.82.95.51 (talk)
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Abstract

OpenWRT is a Linux port (2.4 kernel) for embedded plattforms including the Netgear wgt634u wireless router.

Click is a modular software for implementing advanced router functionality on Linux systems.

Madwifi is a WLAN driver (802.11 wireless network) that runs on OpenWRT and can be integrated with the click system.

This tutorial describes the steps of downloading the source code for each of these 3 components, for compiling them, and for getting them to run (together) on a wgt634 Netgear wireless router platform.

This work has been done for the Berin Roof Net project ( http://sarwiki.informatik.hu-berlin.de/wiki/BerlinRoofNet ), with substantial support from the MIT Roof Net project team ( http://pdos.csail.mit.edu/click/ )

OpenWRT setup

First of all you need to install the openwrt toolchain ( [1] ) on your build computer. 

 cvs -d:pserver:anonymous@openwrt.org:/openwrt login
 cvs -d:pserver:anonymous@openwrt.org:/openwrt co buildroot

The following tools/libs are required:

  • wget, tftp
  • cvs, subversion
  • gcc, gcc-c++, bison, flex
  • patch, gettext
  • autoconf, automake
  • zlib-devel

We need a C++-compiler, so you’ll need to patch $OPENWRT/buildroot/Makefile. 

 INSTALL_LIBSTDCPP:=true

That's all: run make

Compiling click

To build click you have to copy the following Makefile (click.mk) to the $OPENWRT/buildroot/make directory: 

 #############################################################
 #
 # click
 #
 #############################################################
 CLICK_DIR:=$(BUILD_DIR)/click
 
 click-source: $(CLICK_DIR)/.unpacked
 
 
 $(CLICK_DIR)/.unpacked: $(DL_DIR)/$(CLICK_SOURCE)
       (cd $(BUILD_DIR); \
       svn co svn://merkur.sardmn.informatik.hu-berlin.de/click)
       touch $(CLICK_DIR)/.unpacked
 
 
 $(CLICK_DIR)/.configured: $(CLICK_DIR)/.unpacked
       (cd $(CLICK_DIR); rm -rf config.cache; \
               $(TARGET_CONFIGURE_OPTS) \
               CFLAGS="$(TARGET_CFLAGS)" \
               AR_CREATEFLAGS="cru" \
               CLFLAGS=-static \
               CXXFLAGS=-static \
               ./configure \
               --build=i686-pc-linux-gnu \
               --host=mipsel-linux \
               --disable-linuxmodule \
               --enable-brn \
               --disable-ip \
               --enable-wifi \
               --disable-ip \
               --enable-tools=mixed \
       );
       touch  $(CLICK_DIR)/.configured
 
 $(CLICK_DIR)/click: $(CLICK_DIR)/.configured
       $(MAKE) CC=$(TARGET_CC) -C $(CLICK_DIR)
 
 $(TARGET_DIR)/usr/bin/click: $(CLICK_DIR)/click
       install -c $(CLICK_DIR)/userlevel/click $(TARGET_DIR)/usr/bin/click
       $(STRIP) $(TARGET_DIR)/usr/bin/click > /dev/null 2>&1
 
 click: uclibc $(TARGET_DIR)/usr/bin/click 
 
 click-clean: 
       $(MAKE) -C $(CLICK_DIR) clean
       rm -rf $(TARGET_DIR)/usr/bin/click
 
 click-dirclean: 
       rm -rf $(CLICK_DIR)

That's all: run make click to build click. Currently, I only tested the userlevel click binary.

Compiling Madwifi.stripped

The madwifi.stripped driver lets Click directly read and write raw frames from the wireless card, and strips out the usual driver logic. To build the madwifi.stripped driver you have to copy the following Makefile (madwifi.mk) to the $OPENWRT/buildroot/make directory: 

 #############################################################
 #
 # madwifi.stripped
 #
 #############################################################
 MADWIFI_DIR:=$(BUILD_DIR)/madwifi
 
 
 $(DL_DIR)/$(MADWIFI_SOURCE):
       $(WGET) -P $(DL_DIR) $(MADWIFI_SITE)/$(MADWIFI_SOURCE)
 
 madwifi-source: $(DL_DIR)/$(MADWIFI_SOURCE)
 
 $(MADWIFI_DIR)/.unpacked: $(DL_DIR)/$(MADWIFI_SOURCE)
       (cd $(BUILD_DIR); \
       cvs -d :pserver:anoncvs@cvs.pdos.lcs.mit.edu:/cvs login)
       (cd $(BUILD_DIR); \
       cvs -z5 -d :pserver:anoncvs@cvs.pdos.lcs.mit.edu:/cvs co -d madwifi roofnet/release/stripped)
       touch $(MADWIFI_DIR)/.unpacked
 
 $(MADWIFI_DIR)/madwifi: $(MADWIFI_DIR)/.unpacked
       $(MAKE) CC=$(TARGET_CC) TARGET=mips-le-elf KERNELPATH=$(BUILD_DIR)/WRT54GS/release/src/linux/linux/ -C $(MADWIFI_DIR)
 
 $(TARGET_DIR)/usr/bin/madwifi: $(MADWIFI_DIR)/madwifi
       mkdir $(TARGET_DIR)/usr/bin/madwifi/
       cp $(MADWIFI_DIR)/madwifi/driver/ath_pci.o $(TARGET_DIR)/usr/bin/madwifi/
       cp $(MADWIFI_DIR)/madwifi/ath_hal/ath_hal.o $(TARGET_DIR)/usr/bin/madwifi/
       $(STRIP) $(TARGET_DIR)/usr/bin/madwifi/ath_pci.o > /dev/null 2>&1
       $(STRIP) $(TARGET_DIR)/usr/bin/madwifi/ath_hal.o > /dev/null 2>&1
 
 madwifi: uclibc $(TARGET_DIR)/usr/bin/madwifi/
 
 madwifi-clean: 
       $(MAKE) -C $(MADWIFI_DIR) clean
       rm -rf $(TARGET_DIR)/usr/bin/madwifi/
 
 madwifi-dirclean: 
       rm -rf $(MADWIFI_DIR)

That's all: run make madwifi to build the driver.

Compiling New Kernel

To build the linux kernel for the wgt634u-box you have to copy the following Makefile (wgtkernel.mk) to the $OPENWRT/buildroot/make directory: 

 #############################################################
 #
 # linux kernel for wgt634
 #
 #############################################################
 WGTKERNEL_DIR:=$(BUILD_DIR)/wgt634u-1.4.1.8-gpl-src
 WGTKERNEL_SOURCE=wgt634u-1.4.1.8-gpl-src.tar.bz2
 WGTKERNEL_SITE=ftp://downloads.netgear.com/files/GPL
 WGTKERNEL_KERNEL=wgt634u-1.4.1.8-gpl-src/linux-2.4.x
 WGTKERNEL_BROADCOM_SRC=wgt634u-1.4.1.8-gpl-src/broadcom-src
 LINUX_DIR:=$(WGTKERNEL_DIR)/linux-2.4.x
 UCLIBC_DIR:=$(BUILD_DIR)/staging_dir/mipsel-linux-uclibc/
 STAGING_DIR:=$(BUILD_DIR)/staging_dir/
 
 all: wgtkernel
 
 $(DL_DIR)/$(WGTKERNEL_SOURCE):
       $(WGET) -P $(DL_DIR) $(WGTKERNEL_SITE)/$(WGTKERNEL_SOURCE)
 
 $(WGTKERNEL_DIR)/.source: $(DL_DIR)/$(WGTKERNEL_SOURCE)
       bzcat $(DL_DIR)/$(WGTKERNEL_SOURCE) | tar -C $(BUILD_DIR) -xvf - $(WGTKERNEL_KERNEL) $(WGTKERNEL_BROADCOM_SRC)
       touch $(WGTKERNEL_DIR)/.source
 
 wgtkernel: dep zImage
 
 dep: $(WGTKERNEL_DIR)/.source
       $(MAKE) CC=$(TARGET_CC) -C $(WGTKERNEL_DIR)/linux-2.4.x oldconfig include/linux/version.h
       $(MAKE) CC=$(TARGET_CC) -C $(WGTKERNEL_DIR)/linux-2.4.x SRCBASE=$(WGTKERNEL_DIR)/broadcom-src dep
 
 zImage:
       $(MAKE) CC=$(TARGET_CC) -C $(WGTKERNEL_DIR)/linux-2.4.x SRCBASE=$(WGTKERNEL_DIR)/broadcom-src zImage
 
 
 wgtkernel-clean: 
       $(MAKE) -C $(LINUX_DIR) clean
       rm $(WGTKERNEL_DIR)/.unpacked
 
 wgtkernel-dirclean: 
       rm -rf $(WGTKERNEL_DIR)


First, the stock kernel doesn’t link with gcc 3.3.3, so you’ll need to patch linux-2.4.x/arch/mips/brcm-boards/bcm947xx/cfe_flash_nvram.c. 

 @@ -927,6 +927,12 @@
       struct page *page, *end;
       unsigned int i;
 
 +       /* Register char device */
 +       if ((nvram_major = devfs_register_chrdev(252, "nvram", &nvram_fops)) < 0) {
 +               ret = nvram_major;
 +               return ret;
 +       }
 +
         /* Allocate and reserve memory to mmap() */
         while ((PAGE_SIZE << order) < NVRAM_SPACE)
                 order++;
 @@ -955,21 +961,11 @@
         /* Initialize hash table */
         nvram_rehash();
 
 -       /* Register char device */
 -       if ((nvram_major = devfs_register_chrdev(252, "nvram", &nvram_fops)) < 0) {
 -               ret = nvram_major;
 -               goto err;
 -       }
 -
         /* Create /dev/nvram handle */
         nvram_handle = devfs_register(NULL, "nvram", DEVFS_FL_NONE, nvram_major, 0,
                                       S_IFCHR | S_IRUSR | S_IWUSR | S_IRGRP, &nvram_fops, NULL);
         return 0;
 -
 - err:
 -       nvram_exit();
 -       return ret;
  }
 
  module_init(nvram_init);


Third, you’ll need to patch linux-2.4.x/Makefile. 

 27a28,29
 > MIPS_BASE     	= $(TOPDIR)/../../staging_dir/bin/
 > 
 29c31
 < LD		= $(CROSS_COMPILE)ld
 ---
 > LD		= $(MIPS_BASE)/$(CROSS_COMPILE)ld
 32,36c34,38
 < AR		= $(CROSS_COMPILE)ar
 < NM		= $(CROSS_COMPILE)nm
 < STRIP		= $(CROSS_COMPILE)strip
 < OBJCOPY		= $(CROSS_COMPILE)objcopy
 < OBJDUMP		= $(CROSS_COMPILE)objdump
 ---
 > AR		= $(MIPS_BASE)/$(CROSS_COMPILE)ar
 > NM		= $(MIPS_BASE)/$(CROSS_COMPILE)nm
 > STRIP		= $(MIPS_BASE)/$(CROSS_COMPILE)strip
 > OBJCOPY		= $(MIPS_BASE)/$(CROSS_COMPILE)objcopy
 > OBJDUMP		= $(MIPS_BASE)/$(CROSS_COMPILE)objdump


Fourth, you’ll need to patch linux-2.4.x/arch/mips/Makefile. 

 69c69
 < GCCFLAGS	+= -mcpu=r4600 -mips2 -Wa,--trap
 ---
 > GCCFLAGS	+= -mips2 -Wa,--trap
 72c72
 < GCCFLAGS	+= -mcpu=r4600 -mips2 -Wa,--trap
 ---
 > GCCFLAGS	+= -mips2 -Wa,--trap
 75c75
 < GCCFLAGS	+= -mcpu=r4600 -mips2 -Wa,--trap
 ---
 > GCCFLAGS	+= -mips2 -Wa,--trap
 78c78
 < GCCFLAGS	+= -mcpu=r4600 -mips2 -Wa,--trap
 ---
 > GCCFLAGS	+= -mips2 -Wa,--trap
 81c81
 < GCCFLAGS	+= -mcpu=r4600 -mips2 -Wa,--trap
 ---
 > GCCFLAGS	+= -mips2 -Wa,--trap

Fifth, you’ll need to patch linux-2.4.x/arch/mips/brcm-boards/bcm947xx/compressed/Makefile. 

 21d20
 < STRIP := $(CROSS_COMPILE)strip
 23c22,25
 < OBJCOPY		:= $(CROSS_COMPILE)objcopy -O binary -R .reginfo -R .note -R .comment -R .mdebug -S
 ---
 > MIPS_BASE	:= $(TOPDIR)/../../staging_dir/bin/
 > STRIP 		:= $(MIPS_BASE)/$(CROSS_COMPILE)strip
 > 
 > OBJCOPY		:= $(MIPS_BASE)/$(CROSS_COMPILE)objcopy -O binary -R .reginfo -R .note -R .comment -R .mdebug -S
 28c30
 < ASFLAGS		+= -G 0  -mno-abicalls -fno-pic -pipe -mcpu=r4600 -mips2 -Wa --trap -m4710a0kern
 ---
 > ASFLAGS		+= -G 0  -mno-abicalls -fno-pic -pipe -mips2


Last, if you’re planning to run userlevel click, edit the linux-2.4.x/.config file and change the CONFIG_ETHERTAP and CONFIG_TUN lines to y.

That's all: run make wgtkernel to build the kernel.

References

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