uClinux course

1
uClinux course

• Day 2 of 5
• Using configuration tools and the tool chain

2
Configuration tools

• Linux/Unix has a key advantage over windows due
  to its modularity kernel or application
  components can be added or removed easily
• This makes it very suitable to embedded
  environments where many typical PC peripherals
  such as keyboards and screens are not present
• The uClinux configuration script allows kernel
  components and applications to be added and
  removed
• The uClinux environment uses two different menu
  configuration environments
• For X windows environments a graphical menu
  system
• make xconfig
• For terminal environments a text based menu
  system
• Make menuconfig

3
Configuration tools

• type make menuconfig from a terminal window
• Use lttabgt, and ltentergt to navigate through menus
  and ltspacegt to select check boxes

Select Target Platform Selection
Select (..) Vendor/Product To change the host
processor you are compiling for. We will use
(GDB/ARMulator) for the simulator and
(Atmel/AT91) for the real hardware later in the
course
4
Configuration tools

• Selecting Kernel version
• linux-2.4.x or linux-2.0.x depending on the
  size/feature set you need

• Selecting Libc version
• glibc is the original unadapted libc, it is the
  largest library
• uC-libc is the original library for uclinux,
  APIs not always standard some routines not
  present
• uClibc fixes problems with original uC-libc
  although it is a little larger than uC-libc

• If you want to change Kernel settings select the
  check box
• X Customise Kernel Settings (NEW) with ltspacegt
• If you want to add or remove user applications
  select the check box
• X Customise Vendor/User Settings with ltspacegt

• When you are finished highlight Exit and press
  ltEntergt

5
Configurations tools
You are then brought back to this screen and you
ask yourself huh, I chose to change Kernel
settings and all I can do is lt Exit gt or go back
to Target Platform Selection Against all logic
Select lt Exit gt
Whizz , pop .
6
Configurations tools

• Linux Kernel Configuration screen

• Some important options to set
• ltSystem typegt to set up RAM and FLASH addresses
• ltGeneral optionsgt to activate/deactivate
  networking
• ltNetworking optionsgt to choose networking
  protocols

• When you are finished highlight Exit and press
  ltEntergt

7
Configuration tools

• Select ltYesgt to save new kernel configuration

8
Configuration tools

• Customize user settings for uClinux

• Some important options to set
• ltBusy boxgt contains all the common applications
  such as gunzip, grep, ln, chown
• ltNetwork applicationsgt contains common network
  apps such as dhcp, ftp, ifconfig

• When you are finished highlight Exit and press
  ltEntergt

9
Configuration tools

• When you are finished configuring uClinux type
  the following commands to build the kernel and
  the userland
• make dep make
• If you only want to build the userland type
• make user_only
• Make romfs
• make image

• Go and make coffee or take a jog .. This can take
  a few minutes

10
Adding User applications

• Files to edit
• user/Makefile
• Add a line to the file like
• dir_(CONFIG_USER_FOO_FOO) foo
• This adds the directory 'foo' to the list of
  directories to be built. I added
• mine in alphabetical order. The order doesn't
  seem to matter.
• config/Configure.help
• This file contains the text which is presented
  on request during the
• config.
• Add a block like
• CONFIG_USER_FOO_FOO
• This program does fooey things to your bars.
• The text must be indented two spaces, and
  there must be no empty lines. Lines

11
Adding User applications

• config/config.in
• Add a line in the apropriate menu section
  (i.e. in the program group you want
• your app to show up in during 'make config' I
  used 'misc'), like
• bool 'foo' CONFIG_USER_FOO_FOO
• The repetition of FOO allows for directories
  which contain multiple
• executables. Thus, if the user directory 'foo'
  contained code to make 'foo'
• and 'bar', each gets its own config line if an
  additional entry is made like
• bool 'bar' CONFIG_USER_FOO_BAR

12
Adding User applications

• Next, there needs to be a proper
  /user/foo/Makefile. The Makefile should follow
• the following template
• --------------------------------------------
  
• EXEC foo
• OBJS foo.o
• all (EXEC)
• (EXEC) (OBJS)
• (CC) (LDFLAGS) -o _at_ (OBJS) (LDLIBS)
• romfs
• (ROMFSINST) /bin/(EXEC)
• clean
• -rm -f (EXEC) .elf .gdb .o
• ---------------------------------------------

13
Adding User applications

• If more than one executable is built in the foo
  directory, as above, then the
• Makefile should look like
• -----------------------------------------------
  -------------
• EXECS foo bar
• OBJS foo.o bar.o
• all (EXECS)
• (EXECS) (OBJS)
• (CC) (LDFLAGS) -o _at_ _at_.o (LDLIBS)
• romfs
• (ROMFSINST) -e CONFIG_USER_FOO_FOO
  /bin/foo
• (ROMFSINST) -e CONFIG_USER_FOO_BAR
  /bin/bar
• -----------------------------------------------
  ---------------
• More complex makefiles are of course possible.
  The reader is encouraged to
• browse the user tree for examples.

14
Adding User applications

• Assignment 1
• Add an application which prints the following
  on the the stdout display of uClinux use the
  simulator

15
The tool chain
The compile process
cpp
cc1
as
ld