source: rtems/c/src/lib/libbsp/i386/pc386/HOWTO @ d637822

#
#  $Id$
#

Joel's Note:

This has some information which is specific to 3.6.0.  Other parts of the
document should be merged with the main RTEMS READMEs.  Procedures for
building a boot floppy, from a network server, and other information
specific to this BSP should remain in this file.

-----------

RTEMS PC386 BSP HOWTO:

1. Introduction
---------------

    This howto tries to explain how to setup the RTEMS host
environment on a Linux based PC so that RTEMS applications can be
built for and run in a bare PC 386+.

    Please note that everything in the following text using the
notation '<...>' is just an alias to something and should always be
substituted by the real thing!

2. Unarchiving
--------------

    Files which have been "tarred, zipped" (i.e. .tar.gz or .tgz
extension) may be unarchived with a command similar to one of the
following:

      gzcat <file>.tgz | tar xvof -

    OR

      gunzip -c <file>.tgz | tar xvof -

    OR

      gtar xzvf <file>.tgz

    NOTE: gunzip -c is equivalent to gzcat, while gtar is GNU tar.

    Given that the necessary utility programs are installed, any of
the above commands will extract the contents of <file>.tar.gz into the
current directory. All of the RTEMS components will be extracted into
the subdirectory rtems-3.2.0. To view the contents of a component
without restoring any files, use a command similar to the following:

      gzcat <file>.tgz | tar tvf -

3. The building tools (gcc, binutils, et al.)
---------------------------------------------

    The PC386 BSP was developed so that the Linux native building
tools can be used to build the RTEMS binaries.

    With this in mind all you have to do is check if you have gcc +
binutils (as, ld, ar, objcopy) installed in your system (which most
probably you'll have) and check their versions. You can do so with:

    - 'gcc -v' (for gcc);      --> version 2.7.2.1
    - 'ld -v'  (for binutils). --> version 2.8.1 (with BFD linux-2.8.1.0.1)

    The above mentioned versions of gcc and binutils are almost
certainly guaranteed to work (their the ones we've been using). More
recent versions should also be ok, and older versions may be ok too.

    The only known problem is with older versions of binutils which
still don't have a 'binary' target in 'objcopy'. We need objcopy's
binary target to produce our final binaries (this will probably be
enhanced in the future, so we get them directly from the 'elf32-i386'
object, but for now this is how we do it). There's a possible
workaround this, using older versions of 'objdump' with the flags used
to produce the Linux kernel binary. You can investigate this in the
Linux source makefiles. This hasn't been tested.

    It should be ok to build a cross-compilation environment (gcc +
binutils) that supports the 'elf32-i386' target, so that you can use a
host system other than Linux. This hasn't been tested.

    You can get 'gcc' and 'binutils', both pre-compiled binaries for
Linux and sources from:

    ftp://sunsite.unc.edu/pub/Linux/GCC/

      binutils-2.8.1.0.1.bin.tar.gz
      binutils-2.8.1.0.1.tar.gz
      gcc-2.7.2.1.bin.tar.gz

as well as from several other mirrors and sites.

4. Creating aliases for gcc and the binutils
--------------------------------------------

    The NEWLIB expects to be compiled by a cross-compiler. The easiest
(as far as we could find out) way to do this, short of changing the
configuration files is to make symbolic links from cross-compiler
style names (the usual names with a 'i386-elf32-rtems-' prefix) to the
real name.

    You can use the following shell script to create these links
quickly. It assumes that the native Linux 'gcc' and 'binutils' reside
in their usual place (i.e. '/usr/bin/'). It also assumes that you're
running it in the directory where the aliases will reside (which we
will refer to as <elf32-tools>). You should then add <elf32-tools> to
you path. This is necessary for building the NEWLIB package.

--- CUT HERE --- CUT HERE --- CUT HERE --- CUT HERE --- CUT HERE ---

#!sh
ln -sf /usr/bin/ar i386-elf32-rtems-ar
ln -sf /usr/bin/as i386-elf32-rtems-as
ln -sf /usr/bin/cpp i386-elf32-rtems-cpp
ln -sf /usr/bin/gasp i386-elf32-rtems-gasp
ln -sf /usr/bin/gcc i386-elf32-rtems-gcc
ln -sf /usr/bin/ld i386-elf32-rtems-ld
ln -sf /usr/bin/objcopy i386-elf32-rtems-objcopy
ln -sf /usr/bin/objdump i386-elf32-rtems-objdump
ln -sf /usr/bin/ranlib i386-elf32-rtems-ranlib

--- CUT HERE --- CUT HERE --- CUT HERE --- CUT HERE --- CUT HERE ---
 
5. Building Newlib
------------------

    The next step is to build and install the NEWLIB package. The
version we've been using and have tested is:

      newlib-1.7.0-posix-rtems-3.6.0.tgz

    You can get it from:

      ftp://lancelot.gcs.redstone.army.mil/pub/rtems/releases/current/c/

    After unarchiving the NEWLIB distribution (discussed earlier), the
NEWLIB package must be configured for the desired host and target.

    This is accomplished by changing the current directory to the top
level of the NEWLIB source tree and executing the configure script
with the appropriate arguments. This step configures the NEWLIB source
for the 'i386-elf32-rtems' target configuration. The libraries and
include files will be installed at <install_point>. The --verbose
option to the ./configure script is recommended so you can check how
the configuration process is progressing. Meanwhile we must do a
little patching: 'install.sh' and 'config.sub' are missing from the
'libgloss' sub-directory. A command sequence similar to the following
should be used:

      cd newlib-<NEWLIB_Version>

      cp configure.sub libgloss
      cp install.sh libgloss

      CC=gcc CFLAGS="-O4 -g" ./configure --verbose \
             --target=i386-elf32-rtems \
             --prefix=<install_point>

    If the configure script successfully completes, then NEWLIB may be
built. This step builds the NEWLIB package in the local directory and
does NOT install any files. The example commands specifies that gcc
should be used as the C compiler and the arguments to be used by gcc.

    A command similar to the following should be used:

      make CC="gcc" CFLAGS="-O4 -g"

    If the build process successfully completes, then the NEWLIB
package is ready to install. A command similar to the following should
be used:

      make CC="gcc" CFLAGS="-O4 -g" install

    If this successfully completes, then the NEWLIB package has been
installed at <install_point>.

    The documentation for the NEWLIB package is formatted using
TeX. If TeX and some supporting tools are installed on the development
system, then the following command may be used to produce the
documentation in the "DVI" format:

      gmake CC="gcc" CFLAGS="-O4 -g" dvi

    If while the documentation is being formatted, the message "Cross reference values unknown; you must run TeX again." is printed, then the "DVI" files generated by this command (e.g. *.dvi in every subdirectory with documentation) must be removed and the command reexecuted.

6. Modules
----------

    Modules eases the process of manipulating the environment
variables required to build RTEMS. If, for whatever reason, you do not
wish to use Modules, then it will be necessary to manually modify
shell initialization files and set the required RTEMS shell variables
"manually." In this case, the Modules files are still the best place
to look for information on what variables to set and example values.

    The Modules package was utilized by the RTEMS developers to make
the initialization process shell independent. The Modules files used
by the RTEMS developers to configure their user environment while
working on a particular target board are included in the
distribution. These require only simple modifications to be
"localized" for the RTEMS developer. The modifications to these ASCII
files can be made with an editor such as vi or emacs.

    The Modules Homepage is:

      http://www.modules.org/

    You can get the Modules distribution (the latest version, which
we've been using, is '3.0pre') via the homepage or directly from:

      ftp://ftp.modules.org/pub/distrib/Modules-3.0pre.tar.gz


    6.1. New Modules users
    ----------------------

    Install Modules on the development system following the
instructions in the file README in the main Modules directory. When
Modules has been installed and a user account setup to use Modules,
then proceed to the section Current Modules Users.

    6.2. Current Modules users
    --------------------------

    If the host computer already utilizes the Modules package, then
the assistance of the system administrator responsible for the Modules
package will be required to perform the modifications described below.

    The system administrator must integrate the RTEMS modules into the
existing Modules configuration. A first alternative is to copy all of
the module files provided with RTEMS into an existing modulefiles
directory. This requires that future updates of RTEMS modules will
also have to be integrated into the existing modulefiles
directory. This alternative is not recommended.

    The more preferable alternative is to add the RTEMS modulefiles
directory to the MODULEPATH. This can be accomplished on an individual
user or system wide basis. For individual users, the RTEMS modules
directory can be added to the MODULEPATH of those users requiring
access to RTEMS. The default MODULEPATH is established by the Modules
initialization routine. Thus, the RTEMS modules directory must be
added to the MODULEPATH in the user's shell initialization file
(~/.profile or ~/.cshrc for example) following the Modules
initialization statement. The proper way to accomplish this is to use
the Modules use statement. For example, the following line should be
added to the user's shell initialization file:

      module use <rtems_path>/modules/modulefiles

    For system wide access, the RTEMS modulefiles directory can be
added to each of the shell initialization scripts in the existing
Modules package. This will require modifying the initialization of
MODULEPATH in each shell initialization file.

    After integrating RTEMS modules with the existing modules, one may
proceed to the Configuring An RTEMS User section.

7. RTEMS
--------

    You can get the latest free release of the C distribuition of
RTEMS (version 3.6.0), from:

      ftp://lancelot.gcs.redstone.army.mil/pub/rtems/releases/current/c/

    Where you'll find:

      rtems-3.6.0.tgz    or    rtems-c_src.tgz - RTEMS sources;

      rtems-3.5.1-c_doc.tgz or rtems-c_doc.tgz - RTEMS documentation;

      individual_manuals/ - Sub-directory where you can get the
                            manuals individually.

    Please note that the RTEMS documentation is slightly outdated
(most noticeably some RTEMS primitives have different protoypes) since
it refers to the previous release (3.5.1.) of RTEMS.

    After unarchiving the RTEMS distribution (discussed earlier), it
is necessary to add the PC386 BSP to the source tree. This is done in
two steps.

    The first step consists in unarchiving the
'rtems-3.6.0-PC386-BSP.tgz' archive over the standard rtems-3.6.0
distribution. It should be done in the same directory where
'rtems-3.6.0.tgz' was unarchived.

    Next you'll need to apply the patch in
'rtems-3.6.0-PC386-BSP.diff.gz' to the RTEMS source tree. The
following command should be used:

      gzip -d -c rtems-3.6.0-PC386-BSP.diff.gz | patch

also from the same directory where 'rtems-3.6.0.tgz' was unarchived.

    At this stage we have RTEMS + PC386 BSP, the user environment must
be setup to build and install RTEMS.

    Using this process, you'll know which files are patched and which
files are new.

    7.1. Board Support Package
    --------------------------

    A Board Support Package (BSP) is a collection of device drivers,
initialization code, and linker scripts necessary to execute RTEMS on
a particular target board. The minimum set of device drivers for a
single processor target includes a Clock, Console I/O, and Benchmark
Timer device drivers.

    The source code for the PC386 BSP can be found in the directory 'c/src/lib/libbsp/i386/pc386.

    7.2. Makefile Configuration Files
    ---------------------------------

    There are two target specific configuration files used by the
Makefile system. These configuration files specify detailed
information about the toolset, the compilation process, as well as
some general configuration information regarding the target and the
development environment. The following is a list of these
configuration files:

      c/make/compilers/gcc-pc386.cfg

      c/make/custom/pc386.cfg

    If you're compiling to a i386+ with FPU in a standard Linux
environment, you shouldn't require any changes to these files in order
to build RTEMS (though you'll probably want to fine tune them later
on).

    7.3 Creating a Customized Modules File
    --------------------------------------

    Files which the Modules packages may use to customize a user's
environment for building, installing, and modifying RTEMS are found in
the c/Modules/rtems directory. Each of the files in this directory
corresponds to the configuration used by the RTEMS developers for
building and installing RTEMS for a particular target board. These
files contain the Modules commands necessary to set the following
environment variables:

       Variable                      Description

      RTEMS_BSP            The name of the target BSP (e.g.
                                 mvme136 or cvme961).

      RTEMS_ROOT        The full path of root directory of the
                                  RTEMS source code.

    RTEMS_GNUTOOLS     The full path of the root directory for
                         the cross-development toolset to be
                                        used.

      RTEMS_HOST         The name of the operating system for
                               the development system.

    RTEMS_LIBC_DIR     The full path of the root directory for
                          the Standard C Library to be used.


    The Modules file for the PC386 BSP is: 'c/Modules/rtems/nav-pc386'.

    You MUST edit this file and set the following variables to the
correct values in your system:

      - RTEMS_ROOT;
      - RTEMS_GNUTOOLS (this is the directory where the links in 4.
                        were created);
      - RTEMS_LIBC_DIR (this is the directory where the Newlib target
                        specific root is installed, and with reference
                        to 5. should be '<install_point>/i386-elf32-rtems').
 
    7.4 Configuring an RTEMS User Using Modules
    -------------------------------------------

    Each user building and installing RTEMS must have their
environment configured. The user environment must have a set of
variables set in it which indicate the target BSP, host operating
system, and numerous paths.

    If you'll just be using the PC386 BSP then a line of the following
type may be added to the initialization file for your shell after the
Modules initialization statement.

     module load nav-pc386

    Note that you must logout and login before any changes to the shell
initialization files will take effect.

    If you don't wish the RTEMS environment configuration to be added
to your shell initialization file, then the "module load" statement
may be entered at the command line.

    You may switch from one RTEMS configuration to another with either
of the following command sequences:

      module unload <old_rtems_modulefile>
      module load <new_rtems_modulefile>

    OR

      module switch <old_rtems_modulefile> <new_rtems_modulefile>

    The command "module avail" may be used to obtain a list of the
Module files which are available to be loaded using the "module load"
command.

    The command "module list" provides a list of the currently loaded
Modules.
 
    7.5. Building RTEMS
    -------------------

    By default, the PC386 RTEMS BSP is installed into the directory
'c/pc386_i386'. If this is not the desired installation point, then
modify the following line in the file 'c/make/custom/pc386.cfg':

      PROJECT_HOME=$(PROJECT_ROOT)/$(RTEMS_BSP)

    Once the root directory of the install point has been set, the
following steps are required to build and install RTEMS (NOTE: If the
Modules files are used, the environment variable '$r' is set to point
to the top directory for the RTEMS implementation selected in the
current environment. This is the directory 'c' in the RTEMS
distribution.):

      cd $r
      make install

    If this completes successfully, then RTEMS has been built and
installed.

8. RTEMS Tests
--------------

    If you've completed the last step successfully, you'll find the
RTEMS sample and test files in the 'c/pc386_i386/tests' directory.

    The 'sp*.bt' are the single processor tests and should all work
correctly. The same applies to the 'tm*.bt' which are the timing
tests.

    The other sample ('*.bt') files should also work with the
exception of 'spfatal.bt' and 'stackchk.bt' (see 9.).

    To load the '*.bt' files you can either run the 'diskboot.exe'
(which can be found in 'c/pc386_i386/build-tools') under DOS with a
command line like (this is just a quick and dirty loader - you'll have
to press return twice after entering it):

      diskboot sp01.bt

    Alternatively, if you have a PC connected to a network with a
BOOTP server and a TFTP server (this can very well be you're Linux
RTEMS host system), you can use Gero Kuhlmann's netboot loader, to
load RTEMS to a diskless PC across a network. You can get it from:

      ftp://sunsite.unc.edu/pub/Linux/system/boot/netboot-0.7.2.tar.gz

    Follow the instructions contained in the package to setup the
server(s) and to build a boot ROM for the client PC network card, or a
boot diskette, and the client should be able to load the '*.bt' files
from the server.

    For the network loader every relocation address from 0x10200 to
0x80200 are known to work correctly. For the DOS loader, relocation
addresses 0x20200, 0x40200 and 0x80200 are known to work under DOS
5.00, DOS 6.xx and DOS 7.00. You can set the relocation address in
'c/make/compilers/gcc-pc386.cfg' by setting the value of the
'RELOCADDR' variable.
 
9. Important Notes
------------------

    The optional stack checker extension ('stackchk') doesn't seem to
be working properly. It reports blown task stacks even if everything
seems to work properly when 'stackchk' isn't activated... This should
be properly investigated: the problem can reside with the 'PC386 BSP',
or in the interface between 'stackchk' and the BSP (maybe something
isn't being correctly initialized...). Since this doesn't seem to be a
serious BSP problem, it hasn't been dealt with, due to more prioritary
problems.

    The tests which exercise the fatal error mecanisms don't work
correctly either. I've been told by Joe that 'spfatal' is outdated, and
so this really isn't surprising.

    This issues may be important and should be investigated as soon as
possible.

    When programming interrupt handlers take into account that the PIC
is reprogrammed and so you should use the interface functions provided
to garantee that everything works ok.