Mini howto build toolschain and initramfs on Linux

I got some errors when build the cross tool chain

1.

====================================================

src is from linux2nios CD->GUNSRC.TGZ

binutils->OK

gcc->error

elf2flt->OK

here is the gcc error:

 rule to make target `../../../gcc/gcc/config/nios2/lib2-divmod.c', needed by 
`libgcc.mk'.  Stop.
make: Leaving directory `/usr/local/src/nios2/build/gcc/gcc'
make: ***  Error 2

2.

==================================================

windows_src:

binutils->error

gcc->ok

elf2flt->ok

here is the gcc error

...
checking whether ANSI C string concatenation works ... yes
*** ld does not support target nios2-elf
*** see ld/configure.tgt for supported targets
make: ***  Error 1

3.

==================================================

I fount the size of nios2-elf-gcc ar ld ... form inux2nios CD->GUNBIN.TGZ is

larger than the ones that I built out.

i.e.

GUNBIN.TGZ->nios2-elf-gcc 409,858 byte

/usr/local/bin/nios2-elf-gcc 269,679 byte( which is I built out)

but I tested both of them could worke well. Why? Is it the static-library and

dynamic-library?

4.

==================================================

I cannot built out /usr/local/nios2-elf/lib (there are libm.a libc.a ...) and

/usr/local/nios2-elf/include (some *.h files used for C)

In which step are they during building cross tool chain?

Wow, great work hippo.. we shoudl all be thankful you put that time in to summarize it. Our thread does a great job IMO of walking someone through the process, but it's good you summarized it here. Unfortunately, I will be unavailable to add much until the new year... but once I'm back, I will add as much info as I can.

J

Hi J, Happy new year.

More information about Initramfs can be found on LWN, "Initramfs arrives" and

"Patch: Documentation for ramfs, rootfs, initramfs."

Hi Mountain8848,

Which linux distribution do you use?

I have built on Slackware 10.2 and Fedora core4.

You should use gcc 3.xx to build the tools.

There are problems when using gcc 4.xx.

On Redhat/Fedora , there were compat-gcc packages.

cd /usr/bin

mv gcc gcc4

ln -s gcc32 gcc

I didn't use the source from linux nios2 cd.

You maybe right about the exec binary size differeces between them, static/dynamic.

About the libs/includes, there are two sets. The newlib is used by altera IDE as default.

And uClibc is used by busybox/uclinux.

You don't need newlib if most of your works on uclinux.

The uClibc build refers to kernel build include.

You must follow the steps, build kernel before build uCLibc.

The uClibc build in my first post, make install will place the includes and libs into /usr/local/nios2-elf/ include and lib.

I did build both, and install into different dirs.

You can select with -nostdinc and -nostdlib flags.

1. newlib

place the source in /usr/local/src/nios2/ newlib.

after you build the nios2-elf-gcc.

cd /usr/local/src/nios2/newlib/newlib

cp configure.host.smallc configure.host

mkdir /usr/local/src/nios2/build/newlib

cd /usr/local/src/nios2/build/newlib

../../newlib/configure --target=nios2-elf

make

make install

Then the include and lib will be placed in /usr/local/nios2-elf .

2. uClibc

if you install both lib set,

follow the steps, as in the first post. but set the RUNTIME/DEVEL install dirs to another place.

change the UCLIBC_PLUGIN when building busybox, and apps.

This is about modules. We will install the modules tree and update the busybox to use "modprobe".

The busybox in release1.4 from microtronic can not support modules in trees. Download the latest update from http://busybox.net/downloads/snapshots/bus...napshot.tar.bz2 (http://busybox.net/downloads/snapshots/busybox-snapshot.tar.bz2). Newer update has more features and fixs. I used the one built on 20051220.

Place it in /usr/local/src/nios2.

# rename the old busybox, so you can still use it when you need

cd /usr/local/src/nios2

mv busybox busybox-1.00-pre8

tar jxf busybox-snapshot.tar.bz2

cd busybox

Update the Makefile and Rules.mak in busybox.

*** Makefile    2005/12/27 13:07:23    1.1
--- Makefile    2005/12/28 00:46:02
***************
*** 211,219 ****
  
  endif#  ifneq ($(strip $(HAVE_DOT_CONFIG)),y)
  
! busybox: .depend $(libraries-y)
      $(CC) $(EXTRA_CFLAGS) $(LDFLAGS) -o $@ -Wl,--start-group $(libraries-y) $(LIBRARIES) -Wl,--end-group
!  $(STRIPCMD) $@
  
  busybox.links: $(top_srcdir)/applets/busybox.mkll include/bb_config.h $(top_srcdir)/include/applets.h
      - $(SHELL) $^ >$@
--- 211,228 ----
  
  endif#  ifneq ($(strip $(HAVE_DOT_CONFIG)),y)
  
! busybox: busybox.elf
!  nios2-elf-elf2flt -s 16000 -o $@ $<
! 
!# 
!#  Make a relocatable ELF file.
!# 
! %.elf : %.bin
!  $(LD) -T /usr/local/nios2-elf/scripts/elf2flt.ld -Ur -o $@ $<
! 
! busybox.bin: .depend $(libraries-y)
      $(CC) $(EXTRA_CFLAGS) $(LDFLAGS) -o $@ -Wl,--start-group $(libraries-y) $(LIBRARIES) -Wl,--end-group
!#     $(STRIPCMD) $@
  
  busybox.links: $(top_srcdir)/applets/busybox.mkll include/bb_config.h $(top_srcdir)/include/applets.h
      - $(SHELL) $^ >$@
***************
*** 328,334 ****
       docs/busybox pod2htm* *.gdb *.elf *~ core .*config.log 
       docs/BusyBox.txt docs/BusyBox.1 docs/BusyBox.html 
       docs/busybox.net/BusyBox.html busybox.links libbb/loop.h 
!      .config.old busybox
      - rm -rf _install testsuite/links
      - find . -name .\*.flags -exec rm -f {} \;
      - find . -name \*.o -exec rm -f {} \;
--- 337,343 ----
       docs/busybox pod2htm* *.gdb *.elf *~ core .*config.log 
       docs/BusyBox.txt docs/BusyBox.1 docs/BusyBox.html 
       docs/busybox.net/BusyBox.html busybox.links libbb/loop.h 
!      .config.old busybox *.bin
      - rm -rf _install testsuite/links
      - find . -name .\*.flags -exec rm -f {} \;
      - find . -name \*.o -exec rm -f {} \;
*** Rules.mak    2005/12/27 12:56:02    1.1
--- Rules.mak    2005/12/28 00:55:09
***************
*** 72,83 ****
 #  If you are using Red Hat 6.x with the compatible RPMs (for developing under
 #  Red Hat 5.x and glibc 2.0) uncomment the following.  Be sure to read about
 #  using the compatible RPMs (compat-*) at http://www.redhat.com !
!# LIBCDIR:=/usr/i386-glibc20-linux
 # 
 #  For other libraries, you are on your own.  But these may (or may not) help...
!# LDFLAGS+=-nostdlib
!# LIBRARIES:=$(LIBCDIR)/lib/libc.a -lgcc
!# CROSS_CFLAGS+=-nostdinc -I$(LIBCDIR)/include -I$(GCCINCDIR) -funsigned-char
 # GCCINCDIR:=$(shell gcc -print-search-dirs | sed -ne "s/install: \(.*\)/\1include/gp")
  
  WARNINGS=-Wall -Wstrict-prototypes -Wshadow
--- 72,83 ----
 #  If you are using Red Hat 6.x with the compatible RPMs (for developing under
 #  Red Hat 5.x and glibc 2.0) uncomment the following.  Be sure to read about
 #  using the compatible RPMs (compat-*) at http://www.redhat.com !
! LIBCDIR:=/usr/local/nios2-elf
 # 
 #  For other libraries, you are on your own.  But these may (or may not) help...
! LDFLAGS+=-nostdlib  -Wl,-r -Wl,-d -L$(LIBCDIR)/lib $(LIBCDIR)/lib/crt0.o
! LIBRARIES:=-lc -lm -lgcc
! CROSS_CFLAGS+=-nostdinc -I$(LIBCDIR)/include -I/usr/local/src/nios2/build/kernel/include -funsigned-char -iwithprefix include -D__uClinux__
 # GCCINCDIR:=$(shell gcc -print-search-dirs | sed -ne "s/install: \(.*\)/\1include/gp")
  
  WARNINGS=-Wall -Wstrict-prototypes -Wshadow
***************
*** 103,108 ****
--- 103,109 ----
    -e &#39;s/sh/sh/&#39; 
    -e &#39;s/mips-.*/mips/&#39; 
    -e &#39;s/mipsel-.*/mipsel/&#39; 
+      -e &#39;s/nios2-.*/nios2nommu/&#39; 
    -e &#39;s/cris.*/cris/&#39; 
    )
  endif

make menuconfig

make

make install

The .config of busybox must have,

##  Build Options# 
CONFIG_STATIC=y
CONFIG_LFS=y
USING_CROSS_COMPILER=y
CROSS_COMPILER_PREFIX="nios2-elf-"
EXTRA_CFLAGS_OPTIONS="-Dfork=vfork"
CONFIG_FEATURE_SUSv2=y
CONFIG_FEATURE_SUSv2_OBSOLETE=y
# #  Installation Options# #  CONFIG_INSTALL_NO_USR is not set
CONFIG_INSTALL_APPLET_SYMLINKS=y#  CONFIG_INSTALL_APPLET_HARDLINKS is not set#  CONFIG_INSTALL_APPLET_DONT is not set
PREFIX="/usr/local/src/nios2/build/rootfs"

If your nios2 does not have hw mul, add "-mno-hw-mul" to extra cflags above.

If your nios2 does have hw mulx, add "-mhw-mulx" to extra cflags above.

"-mhw-mul" is the default.

Next, we will update the kernel Makefile, and install modules into rootfs.

cd /usr/local/src/nios2/linux-2.6.x

Update Makefile ,as it should be in newer kernels.

*** Makefile~    2005-12-16 11:19:34.000000000 +0800
--- Makefile    2005-12-27 13:34:02.000000000 +0800
***************
*** 894,900 ****
  ifeq "$(strip $(INSTALL_MOD_PATH))" ""
  depmod_opts    :=
  else
! depmod_opts    := -b $(INSTALL_MOD_PATH)/lib/modules -r
  endif
  .PHONY: _modinst_post
  _modinst_post: _modinst_
--- 894,900 ----
  ifeq "$(strip $(INSTALL_MOD_PATH))" ""
  depmod_opts    :=
  else
! depmod_opts    := -b $(INSTALL_MOD_PATH) -r
  endif
  .PHONY: _modinst_post
  _modinst_post: _modinst_

make ARCH=nios2nommu O=/usr/local/src/nios2/build/kernel CROSS_COMPILE=nios2-elf- INSTALL_MOD_PATH=/usr/local/src/nios2/build/rootfs# ## update the rootfs with modules added

make ARCH=nios2nommu O=/usr/local/src/nios2/build/kernel CROSS_COMPILE=nios2-elf-

You should enable modules support in kernel, and module utilities (insmod,rmmod,lsmod,modprobe) in busybox.

The kerenl modules tree will be installed into the INSTALL_MOD_PATH/lib/modules/2.6.11-uc0/kernel/... and modules.dep will be generated.

Then the "modprobe" command will work now. eg

modprobe vfat

will load fs/fat/fat.ko and fs/vfat/vfat.ko.

If you have CF/Microdrive/IDE or other block devices, you can use it to store the modules. Either,

1. Mount it as root, without initramfs. Flash devices are not recommand for root, because of the limited write life. Config the kernel command line to "root=/dev/hda1", and disable initramfs. You should have the device driver and file system compiled in, instead of modules. The FAT/VFAT does not support symlink, and can not be used as root if you want busybox. Consider minix if the root part size <64MB, or ext2 for larger disk. Mount and copy the rootfs to your device, with cp -a.

2. Mount it as /lib, over the initramfs, and keep the initramfs small. Change the modules install path to another dir, then cd lib of this and cp -a to the devices.

The ext3 and reiserfs still have some problem in kernel compilation.

I am checking.

Patch to support minix for /usr/local/src/nios2/linux-2.6.x/include/asm-nios2nommu/bitops.h

*** bitops.h    2005/11/10 06:55:12    1.1
--- bitops.h    2005/11/10 06:56:58
***************
*** 469,472 ****
--- 469,479 ----
 # define ext2_find_first_zero_bit find_first_zero_bit
 # define ext2_find_next_zero_bit  find_next_zero_bit
  
+ /* Bitmap functions for the minix filesystem.  */
+# define minix_test_and_set_bit(nr,addr) test_and_set_bit(nr,addr)
+# define minix_set_bit(nr,addr) set_bit(nr,addr)
+# define minix_test_and_clear_bit(nr,addr) test_and_clear_bit(nr,addr)
+# define minix_test_bit(nr,addr) test_bit(nr,addr)
+# define minix_find_first_zero_bit(addr,size) find_first_zero_bit(addr,size)
+ 
 # endif /* _ASM_NIOS_BITOPS_H */

Could you provide unified patches for this? Maybe it&#39;s time to refresh the patches for buildroot; though I most of the changes seem already available.

I think it would be really nice if we could unify these efforts to have a native GNU/Linux toolchain, since commercially noone seems to be interested in this (resulting IMHO in less good systems: it simply does not make sense developing Linux on a Windows machine, it&#39;s like trying to join the traffic on a highway with a bicycle).

Hi marc,

I&#39;d like to thank you for the great help from your site. I would join with you to work out a better tools/apps building on Linux. Let me know what I can help.

I will make unified diff. The Emacs is default to context diff. I just set it to unified mode.

Do you have progress to build busybox and apps inside buildroot yet?

--- Quote Start ---

originally posted by hippo@Dec 28 2005, 03:06 PM

do you have progress to build busybox and apps inside buildroot yet?

--- Quote End ---

As for busybox, that should not be much of a problem; but since we have a perl build environment for other platforms that builds busybox seperately; I kept busybox out of buildroot.

As long as the applets are supported by the arch of course; the same goes (basically) for the other apps in buildroot. Some will work with or without modifications others will not. I haven&#39;t done much work there; since we shifted back to MMU archs (decisions above my head).

I could only agree that MMU makes the different.

Again the patch to support minx in unified diff.

linux-2.6.x/include/asm-nios2nommu/bitops.h

--- bitops.h    2005/11/10 06:55:12    1.1
+++ bitops.h    2005/11/10 06:56:58
@@ -469,4 +469,11 @@
# define ext2_find_first_zero_bit find_first_zero_bit
# define ext2_find_next_zero_bit  find_next_zero_bit
 
+/* Bitmap functions for the minix filesystem.  */
+#define minix_test_and_set_bit(nr,addr) test_and_set_bit(nr,addr)
+#define minix_set_bit(nr,addr) set_bit(nr,addr)
+#define minix_test_and_clear_bit(nr,addr) test_and_clear_bit(nr,addr)
+#define minix_test_bit(nr,addr) test_bit(nr,addr)
+#define minix_find_first_zero_bit(addr,size) find_first_zero_bit(addr,size)
+
# endif /* _ASM_NIOS_BITOPS_H */

About the busybox, you can also use the stable release 1.01.

http://busybox.net/downloads/busybox-1.01.tar.bz2 (http://busybox.net/downloads/busybox-1.01.tar.bz2)

With the patch.

--- modutils/insmod.c    2005/12/28 11:32:46    1.1
+++ modutils/insmod.c    2005/12/28 11:33:20
@@ -4022,7 +4022,7 @@
 
  fstat(fd, &st);
  len = st.st_size;
-    map = mmap(NULL, len, PROT_READ, MAP_SHARED, fd, 0);
+    map = mmap(NULL, len, PROT_READ, MAP_PRIVATE, fd, 0);
  if (map == MAP_FAILED) {
      bb_perror_msg_and_die("cannot mmap `%s'", filename);
  }
--- Makefile    2005/12/28 09:14:17    1.1
+++ Makefile    2005/12/28 13:16:09
@@ -123,9 +123,18 @@
 include $(patsubst %,%/Makefile.in, $(SRC_DIRS))
 -include $(top_builddir)/.depend
 
-busybox: $(ALL_MAKEFILES) .depend include/config.h $(libraries-y)
+busybox: busybox.elf
+    $(APP_PLUGIN)/bin/elf2flt -s 16000 -o $@ $<
+
+#
+# Make a relocatable ELF file.
+#
+%.elf : %.bin
+    $(LD) -T $(APP_PLUGIN)/scripts/elf2flt.ld -Ur -o $@ $<
+
+busybox.bin: $(ALL_MAKEFILES) .depend include/config.h $(libraries-y)
  $(CC) $(LDFLAGS) -o $@ -Wl,--start-group $(libraries-y) $(LIBRARIES) -Wl,--end-group
-    $(STRIPCMD) $@
+#    $(STRIPCMD) $@
 
 busybox.links: $(top_srcdir)/applets/busybox.mkll include/config.h $(top_srcdir)/include/applets.h
  - $(SHELL) $^ >$@
@@ -272,7 +281,7 @@
      docs/busybox pod2htm* *.gdb *.elf *~ core .*config.log 
      docs/BusyBox.txt docs/BusyBox.1 docs/BusyBox.html 
      docs/busybox.net/BusyBox.html busybox.links libbb/loop.h 
-     .config.old .hdepend busybox
+     .config.old .hdepend busybox *.bin
  - rm -rf _install
  - find . -name .\*.flags -exec rm -f {} \;
  - find . -name \*.o -exec rm -f {} \;
--- Rules.mak    2005/12/28 09:17:00    1.1
+++ Rules.mak    2005/12/28 13:34:54
@@ -71,12 +71,13 @@
#  If you are using Red Hat 6.x with the compatible RPMs (for developing under
#  Red Hat 5.x and glibc 2.0) uncomment the following.  Be sure to read about
#  using the compatible RPMs (compat-*) at http://www.redhat.com !
-#LIBCDIR:=/usr/i386-glibc20-linux
+LIBCDIR?=$(UCLIBC_PLUGIN)
+KERNEL_INCLUDE=$(shell echo $(KERNEL_BUILD_DIRECTORY))/include
# 
#  For other libraries, you are on your own.  But these may (or may not) help...
-#LDFLAGS+=-nostdlib
-#LIBRARIES:=$(LIBCDIR)/lib/libc.a -lgcc
-#CROSS_CFLAGS+=-nostdinc -I$(LIBCDIR)/include -I$(GCCINCDIR)
+LDFLAGS+=-nostdlib  -Wl,-r -Wl,-d -L$(LIBCDIR)/lib $(LIBCDIR)/lib/crt0.o
+LIBRARIES:=$(LIBCDIR)/lib/libc.a -lgcc
+CROSS_CFLAGS+=-nostdinc -I$(LIBCDIR)/include -I$(KERNEL_INCLUDE) -funsigned-char -iwithprefix include -D__uClinux__
# GCCINCDIR:=$(shell gcc -print-search-dirs | sed -ne "s/install: \(.*\)/\1include/gp")
 
 WARNINGS=-Wall -Wstrict-prototypes -Wshadow
@@ -96,6 +97,7 @@
      -e &#39;s/sh/sh/&#39; 
      -e &#39;s/mips-.*/mips/&#39; 
      -e &#39;s/mipsel-.*/mipsel/&#39; 
+  -e &#39;s/nios2-.*/nios2nommu/&#39; 
      -e &#39;s/cris.*/cris/&#39; 
      )
 endif

Or use the snapshot.

http://busybox.net/downloads/busybox-snapshot.tar.bz2 (http://busybox.net/downloads/busybox-snapshot.tar.bz2)

With the patch.

--- Makefile    2005/12/27 13:07:23    1.1
+++ Makefile    2005/12/28 14:52:08
@@ -211,9 +211,18 @@
 
 endif#  ifneq ($(strip $(HAVE_DOT_CONFIG)),y)
 
-busybox: .depend $(libraries-y)
+busybox: busybox.elf
+    $(APP_PLUGIN)/bin/elf2flt -s 16000 -o $@ $<
+
+#
+# Make a relocatable ELF file.
+#
+%.elf : %.bin
+    $(LD) -T $(APP_PLUGIN)/scripts/elf2flt.ld -Ur -o $@ $<
+
+busybox.bin: .depend $(libraries-y)
  $(CC) $(EXTRA_CFLAGS) $(LDFLAGS) -o $@ -Wl,--start-group $(libraries-y) $(LIBRARIES) -Wl,--end-group
-    $(STRIPCMD) $@
+#    $(STRIPCMD) $@
 
 busybox.links: $(top_srcdir)/applets/busybox.mkll include/bb_config.h $(top_srcdir)/include/applets.h
  - $(SHELL) $^ >$@
@@ -328,7 +337,7 @@
      docs/busybox pod2htm* *.gdb *.elf *~ core .*config.log 
      docs/BusyBox.txt docs/BusyBox.1 docs/BusyBox.html 
      docs/busybox.net/BusyBox.html busybox.links libbb/loop.h 
-     .config.old busybox
+     .config.old busybox *.bin
  - rm -rf _install testsuite/links
  - find . -name .\*.flags -exec rm -f {} \;
  - find . -name \*.o -exec rm -f {} \;
--- Rules.mak    2005/12/27 12:56:02    1.1
+++ Rules.mak    2005/12/28 14:53:39
@@ -72,12 +72,13 @@
#  If you are using Red Hat 6.x with the compatible RPMs (for developing under
#  Red Hat 5.x and glibc 2.0) uncomment the following.  Be sure to read about
#  using the compatible RPMs (compat-*) at http://www.redhat.com !
-#LIBCDIR:=/usr/i386-glibc20-linux
+LIBCDIR?=$(UCLIBC_PLUGIN)
+KERNEL_INCLUDE=$(shell echo $(KERNEL_BUILD_DIRECTORY))/include
# 
#  For other libraries, you are on your own.  But these may (or may not) help...
-#LDFLAGS+=-nostdlib
-#LIBRARIES:=$(LIBCDIR)/lib/libc.a -lgcc
-#CROSS_CFLAGS+=-nostdinc -I$(LIBCDIR)/include -I$(GCCINCDIR) -funsigned-char
+LDFLAGS+=-nostdlib  -Wl,-r -Wl,-d -L$(LIBCDIR)/lib $(LIBCDIR)/lib/crt0.o
+LIBRARIES:=$(LIBCDIR)/lib/libc.a -lgcc
+CROSS_CFLAGS+=-nostdinc -I$(LIBCDIR)/include -I$(KERNEL_INCLUDE) -funsigned-char -iwithprefix include -D__uClinux__
# GCCINCDIR:=$(shell gcc -print-search-dirs | sed -ne "s/install: \(.*\)/\1include/gp")
 
 WARNINGS=-Wall -Wstrict-prototypes -Wshadow
@@ -103,6 +104,7 @@
      -e &#39;s/sh/sh/&#39; 
      -e &#39;s/mips-.*/mips/&#39; 
      -e &#39;s/mipsel-.*/mipsel/&#39; 
+  -e &#39;s/nios2-.*/nios2nommu/&#39; 
      -e &#39;s/cris.*/cris/&#39; 
      )
 endif

The .config must has,

##  Build Options# 
CONFIG_STATIC=y
CONFIG_LFS=y
USING_CROSS_COMPILER=y
CROSS_COMPILER_PREFIX="nios2-elf-"
EXTRA_CFLAGS_OPTIONS="-Dfork=vfork"
# #  Installation Options# #  CONFIG_INSTALL_NO_USR is not set
PREFIX="/usr/local/src/nios2/build/rootfs"

Then build,

make UCLIBC_PLUGIN=/usr/local/nios2-elf APP_PLUGIN=/usr/local/nios2-elf KERNEL_BUILD_DIRECTORY=/usr/local/src/nios2/build/kernel menuconfig
make UCLIBC_PLUGIN=/usr/local/nios2-elf APP_PLUGIN=/usr/local/nios2-elf KERNEL_BUILD_DIRECTORY=/usr/local/src/nios2/build/kernel 
make UCLIBC_PLUGIN=/usr/local/nios2-elf APP_PLUGIN=/usr/local/nios2-elf KERNEL_BUILD_DIRECTORY=/usr/local/src/nios2/build/kernel install

This is about how to update uClibc to 0.9.28 stable release.

http://www.uclibc.org/downloads/uclibc-0.9.28.tar.bz2 (http://www.uclibc.org/downloads/uclibc-0.9.28.tar.bz2)

You should config the lib install dir to a new place.

And change the UCLIBC_PLUGIN for busybox and apps to this new place.

You should turn on "wide char support" in "string and stdio support" for busybox to work.

After installed the new uclibc, make clean and rebuild busybox and apps.

Then update kernel image with initramfs.

The daily snapshot of uClibc is still broken for nios2.

Patch,

--- Rules.mak    2005/12/29 07:20:49    1.1
+++ Rules.mak    2005/12/30 01:43:32
@@ -266,7 +266,9 @@
#  If -msoft-float isn't supported, we want an error anyway.
#  Hmm... might need to revisit this for arm since it has 2 different
#  soft float encodings.
+ifneq ($(strip $(TARGET_ARCH)),nios2)
     CPU_CFLAGS += -msoft-float
+endif
 ifeq ($(strip $(TARGET_ARCH)),arm)
#  No longer needed with current toolchains, but leave it here for now.
#  If anyone is actually still using gcc 2.95 (say), they can uncomment it.
--- libc/sysdeps/linux/nios2/crt0.S    2005/12/29 07:03:01    1.1
+++ libc/sysdeps/linux/nios2/crt0.S    2005/12/30 03:07:54
@@ -6,7 +6,8 @@
  * This file is subject to the terms and conditions of the GNU Lesser
  * General Public License.  See the file COPYING.LIB in the main
  * directory of this archive for more details.
  *
  * Written by Wentao Xu <wentao@microtronix.com>
+ * udpated by hippo  for  uClibc 0.9.28 and newer
  * 
  */
@@ -18,7 +19,8 @@
     .type   __start,@function
     .weak   _init
     .weak   _fini
-    .type   __uClibc_start_main,@function
+    .type   main,@function
+    .type   __uClibc_main,@function
     .type   __h_errno_location, @function
     .type   _stdio_init, @function
     .type   _stdio_term, @function
@@ -36,9 +38,10 @@
     addi gp, gp, %lo(_gp)
 
     /* load argc, argv, envp from stack */
-    ldw r4, 0(sp)
-    ldw r5, 4(sp)
-    ldw r6, 8(sp)
+    movhi r4, %hi(main)
+    ori  r4, r4, %lo(main)    /* main */
+    ldw r5, 0(sp)  /* argc */
+    ldw r6, 4(sp)  /* argv */
     
     /* load the 4th arg */
     movhi r7, %hi(_init)
@@ -48,17 +51,19 @@
     movhi r8, %hi(_fini)
     ori  r8, r8, %lo(_fini)
     stw  r8, 0(sp)
-   
+    stw  r2, 4(sp)  /* rtld_fini */
+    stw  sp, 8(sp)  /* stack_end */
+    
     /* call uClibc_main, shouldn&#39;t return */
# ifdef __PIC__
     /* just pray 16 bit offset is enough */
-    br __uClibc_start_main
+    br __uClibc_main
# else
-    call __uClibc_start_main
+    call __uClibc_main
# endif
 
     /* crash in the event of return */
 __exit:
     movui r2, TRAP_ID_SYSCALL
     movui r3, __NR_exit
-    trap
+    trap

Run,

#fix for autoconf.h
make ARCH_CFLAGS="-I(your kernel build/include)" menuconfig
make ARCH_CFLAGS="-I(your kernel build/include)"
make ARCH_CFLAGS="-I(your kernel build/include)" install

The .config must have,

##  Target Architecture Features and Options# 
KERNEL_SOURCE="your kernel source linux-2.6.x"# #  uClibc development/debugging options# 
CROSS_COMPILER_PREFIX="nios2-elf-"