SMP HiFi 2 Development Board

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This is a "community" guide for how to use the LX200 board based 3-core SMP HiFi-2 Development environment. If something doesn't work or isn't covered in this guide, please feel free to ask at the Linux/Xtensa Mailing List.

NEWS:

Some general notes on these instructions:

  • They are a work in progress; almost complete.
  • The following was tested on x86 machines running RedHat Fedora Core 5 and Fedora Core 9.


Introduction

This document is addressed to someone who received an LX200 board setup by Tensilica for HiFi2 development.

This document goes over the steps needed to set up the LX200 board for HiFi2 development. To summarize:

  • Setup the board. It likely comes with U-boot preinstalled, ready to boot a linux kernel.
  • Install git.
  • Download buildroot and linux kernel trees, pre-configured and built for HiFi-2 development.
  • Setup a TFTP server to provide the linux kernel to U-Boot.
  • Setup an NFS server to export a linux root file system.
  • Setup the Linux kernel to boot from the root file system provided by the NFS server.

Once the development board is up and running, this document:

  • Suggests a possible way to tailor the board for easy codec development.
  • Shows how to add the Tensilica provided codec packages to the Mplayer packages used by Buildroot, including building and installing.
  • Demonstrates two procedures for compiling, linking, and debugging codecs.

All development is expected to be done on a Linux host. (One can in principle use Windows to develop target libraries. However, linking and subsequent steps need to be done in Linux.)


Downloading the Latest HiFi-2 Buildroot and Kernel Snapshots

The HiFi-2 development environment is maintained in a source code version control system named 'git'. The git tools are useful when working with this development environment, though they are not strictly necessary. This document generally assumes the use of git, which provides more opportunities for modifying this environment as needed (e.g. building more optional buildroot packages). But points out alternatives to allow getting up and running without having to set it up.

Installing git

To install git, download a recent tarball from the official site. For example, cd to a location with enough disk space, and do: 

       $ wget http://www.kernel.org/pub/software/scm/git/git-1.6.5.tar.gz

Unpack the tarball, and make and install it. Here we show how to install it to your ~/bin directory: 

       $ gunzip git-1.6.5.tar.gz
       $ tar xf git-1.6.5.tar
       $ cd git-1.6.5
       $ make
       $ make install

The git makefile can be instructed to install git to /usr/local/bin as root for system wide access: 

       $ cp git-1.6.5.tar.gz /tmp
       $ su
       Password: 
       # cd /usr/local/src/
       # mkdir git
       # cd git
       # cp /tmp/git-1.6.5.tar.gz .
       # gunzip git-1.6.5.tar.gz
       # tar xf git-1.6.5.tar
       # cd git-1.6.5
       # make prefix=/usr/local
       # make install

See the 'INSTALL instruction at the top of the git src directory for details.


Using git provides easy access to the binaries used to bring up the codec development environment, and leaves in place the infrastructure to modify and build this environment should you wish to. Any changes to git-managed source trees are easily observed with the git tools.

Installing the Buildroot Snapshot

Note: The HiFi-2 snapshot is in the process of being made.

To install the buildroot environment (toolchain and root filesystem), cd to a location with a few GB of available disk space, and do: 

   $ git clone git://git.linux-xtensa.org/git/buildroot/buildroot-xtensa-HiFi2-Snapshot
   $ cd buildroot-xtensa-HiFi2-Snapshot
   $ git branch --track snapshot_2+SMP origin/snapshot_2+SMP 
   $ git checkout snapshot_2+SMP

The last two lines checkout the latest branch (preconfigured for the 3-core HiFi2 on the LX200).

You can examine the tree (git repository) and its history visually using git gui. The git GUI is a faster and more convenient method for checking out the HiFi-2 snapshot. To check out the snapshot_2+SMP branch simply run the command 'git gui' and then pull down the branch->create menu. Next select <>Match Tracking Branch Name and click on origin/snapshot_2+SMP. Finally hit the Create Button. 

   $ git gui                                                                        
      [Branch] -> Create...                                                                  
         <> Match Tracking Branch Name                                                     
         <> Tracking Branch                                                                 
               origin/snapshot_2+SMP                                                         
         [Create]                                                                            
     [Reposirory]--> Quit

If there are issues installing git, as a last resort, an alternative is ftp (may not always get updated, is currently our of date, waste disk space, so may be dropped at some point): 

        http://www.linux-xtensa.org/pub/snapshots/buildroot-xtensa-smp.2-Nov-2009.tar.gz


Installing the Linux Kernel Snapshot

To install the Linux kernel environment (kernel src, config, and HiFi-2 kernel U-Boot image), cd to a location with a few GB of available disk space, and do: 

   $ git clone git://git.linux-xtensa.org/git/kernel/xtensa-2.6.29-smp
   $ cd kernel/xtensa-2.6.29-smp
   $ git branch --track snapshot_2+SMP origin/snapshot_2+SMP                                    [NOTE: Alternate snapshot_2+SMP-stable]
   $ git checkout snapshot_2+SMP

The last two lines checkout the latest branch (preconfigured for the 3-core HiFi2 on the LX200). There is also a more up-to-date branch named snapshot_2+SMP-stable that has more recent kernel bug-fixes from kernel.org but it hasn't been tested extensively and hasn't yet been shown to be any more or less stable than the well tested snapshot_2+SMP branch.

As in the build root case, you can also checkout the branch easily from via git gui using the same procedure mentioned above.

Now, assuming we are still in the kernel xtensa-2.6.29-smp directory copy the kernel U-Boot Image (uImage) to the tftp directory; Ex: 

   $ cp arch/xtensa/boot/uImage /tftpboot/uImage.xtensa-2.6.29-smp.test_mmuhifi_c3               [Note: You make have to make dir /tftpboot]

NOTE: On some system, like Fedora Core 9, the tftpboot directory has been moved to /var/lib/tftpboot. In this case we recommend that you just added a symbolic pointer from /etc to /var/lib/tftpboot: 

   $ su
   # cd /etc
   # /var/lib/tftpboot/ tftpboot
   # ls -ld tftpboot
       lrwxrwxrwx 1 root root 18 2009-11-23 21:14 tftpboot -> /var/lib/tftpboot/
   #

Setting up a TFTP Server to provide the Linux kernel to U-Boot

The TFTP service is part of the xinetd and is installed on Fedora workstations. You can see that it's installed with the check config command which manages the /etc/rc.d/init.d startup scripts and with the yum search command: 

    $ chkconfig --list
       NetworkManager  0:off   1:off   2:off   3:off   4:off   5:off   6:off
       NetworkManagerDispatcher        0:off   1:off   2:off   3:off   4:off   5:off   6:off
       acpid           0:off   1:off   2:off   3:on    4:on    5:on    6:off
       .
       .
       .
       xfs             0:off   1:off   2:on    3:on    4:on    5:on    6:off
       xinetd          0:off   1:off   2:off   3:on    4:on    5:on    6:off
       ypbind          0:off   1:off   2:off   3:on    4:on    5:on    6:off
       yum             0:off   1:off   2:off   3:off   4:off   5:off   6:off

       xinetd based services:
               amanda:         off
               auth:           off
               .
               .
               .
               rsync:          off
               tftp:           on                                                      [NOTE that tftp is enabled]
               time:           off
               time-udp:       off
               uucp:           off
      $
      $
      $
      $ yum search tftp-server
       Loading "installonlyn" plugin
       Searching Packages:
       .
       .
       .
       Reading repository metadata in from local files
       .
       .
       .
       tftp-server.i386                         0.41-1.2.1             installed       [NOTE that tftp server is installed as part of the inet daemon]
       Matched from:
       tftp-server
       The Trivial File Transfer Protocol (TFTP) is normally used only for
       booting diskless workstations.  The tftp-server package provides the
       server for TFTP, which allows users to transfer files to and from a
       remote machine. TFTP provides very little security, and should not be
       enabled unless it is expressly needed.  The TFTP server is run from
       /etc/xinetd.d/tftp, and is disabled by default on Red Hat Linux systems.
       [piet@pdelaney_fc5 ~]$


TFTP is not normally enabled, to enable it just edit the file /etc/xinetd.d/tftp and change the disable field to no: 

       # default: off
       # description: The tftp server serves files using the trivial file transfer \
       #       protocol.  The tftp protocol is often used to boot diskless \
       #       workstations, download configuration files to network-aware printers, \
       #       and to start the installation process for some operating systems.
       service tftp
       {
               socket_type             = dgram
               protocol                = udp
               wait                    = yes
               user                    = root
               server                  = /usr/sbin/in.tftpd                                        [NOTE: /var/lib/tftpboot on Fedora Core 9]
               server_args             = -s /tftpboot
               disable                 = no
               per_source              = 11
               cps                     = 100 2
               flags                   = IPv4
       }


Setting up an NFS Server to export the Root Filesystem

The LX200 board running Linux needs to mount its root filesystem over NFS. This file system was built using buildroot into a cpio format file, and left in: 

   buildroot-xtensa-HiFi2-Snapshot/buildroot-xtensa-smp/binaries/HiFi-2/rootfs.xtensa_test_mmuhifi_c3.cpio.gz

We will also be adding an additional small files-systems to make your development environment more comfortable and less time consuming to get started: 

   /usr/default                                                                           [Home Directory for user 'default']
   /usr/local                                                                             [File system to place enhancments not done by buildroot]


Pick a place on your workstation to export your boards file-systems and unpack the cpio and tar files. For example here we will export three files-systems in /export: 

   /exports/LINUX_ROOT.HiFi-2_DemoBoard.buildroot-xtensa-smp
   /exports/hifi-2_home_default
   /exports/hifi-2_usr_local

Here's and example of unpacking the three files-systems: 

   $ cd buildroot-xtensa-HiFi2-Snapshot/buildroot-xtensa-smp/binaries/HiFi-2        [Getting binary files in buildroot git repository]
   $
   $ gunzip rootfs.xtensa_test_mmuhifi_c3.cpio.gz                                   [Uncompressing file-system cpio file]
   $ gunzip hifi-2_home_default.tar.gz                                              [Uncompress /home/default tar ball]
   $ gunzip hifi-2_usr_local.tar.gz                                                 [Uncompress /usr/local tar ball]
   $
   $ WHERE=$PWD
   $ mkdir -p /exports/LINUX_ROOT.HiFi-2
   $
   $ cd /exports/LINUX_ROOT.HiFi-2
   $ cpio -i < $WHERE/rootfs.xtensa_test_mmuhifi_c3.cpio
   $
   $ cd /export
   $ tar xf hifi-2_home_default.tar                                                 [Tar in boards /home/default for export]
   $ tar xf hifi-2_usr_local.tar                                                    [Tar in boards /usr/local for export]

Next add two lines to /etc/exports: 

   /exports                *(rw,no_root_squash,sync,no_wdelay)                            [Boards Filesystems]
   /export                 *(rw,no_root_squash,sync,no_wdelay)                            [Buildroot source code]

and restart you nfs services: 

   $ /etc/rc.d/init.d/nfs restart

or 

   $ /sbin/chkconfig nfs on

The showmount command should show your NFS file system now being exported: 

   $ showmount -e
     Export list for mypc.foobar.com:
     /export  *
     /exports *
   $

Configuring U-Boot to Boot Linux

Your LX200 board should have arrived with U-Boot installed in the flash ready to use. The board has a DIP switch (next to the power on/off switch) that provides the 6 LSBs of the Ethernet MAC, in switch positions 1 thru 6. 

             DIP Swithes for MAC: 1 2 3 4 5 6 7 8    ethaddr=00:50:C2:13:6f:0a
             Little Endian:       0 1 0 1 0 0 * *
                                                ^
                                                |
                                                +------ Enables booting U-Boot from Flash

DIP switch 8 should be shipped in the ON position to enable U-Boot booting from flash. See Sections 4.2.3 and 4.2.4 of the Tensilica Avnet (XT-AV200) Board User's Guide for details. Make sure to select a unique MAC address for you board.

Next, connect a serial interface to a text based terminal emulation program, set to 38400 bps, no parity, 1 stop bit, no handshaking. For an example of setting minicom for this, see here.

Here's how to configure U-Boot to automatically boot the Linux kernel on power-up (using the root file system exported over NFS as described further above). 

   U-Boot> setenv serverip 192.168.11.55                                                                        [TFTP server IP Address: RTOS-LAB2]
   U-Boot> setenv nfsroot_server 192.168.11.55                                                                  [Root NFS Servers IP Address: My Workstation]
   U-Boot> setenv ipaddr 192.168.11.155                                                                         [HOST IP address]
   U-Boot> setenv bootfile uImage.xtensa-2.6.29-smp.test_mmuhifi_c3                                             [File to fetch with TFTP and pass to bootm]
   U-Boot> setenv root-path /exports/LINUX_ROOT.HiFi-2                                                          [WARNING: Limit path to < 50 characters]
   U-Boot> setenv bootargs_using_bootp console=ttyS0,38400 ip=bootp root=nfs coredump_filter=0xff               [Args passed to Linux while booting with BOOTP proto]
   U-boot> setenv bootargs console=ttyS0,38400 ip=dhcp root=/dev/nfs rw nfsroot=${nfsroot_server}:${root-path}  [Args passed to Linux while booting with DHCP proto]
   U-boot> setenv bootcmd tftpboot\; bootm                                                                      [Boot Linux after fetching it with TFTP]
   U-Boot> setenv bootdelay 20                                                                                  [Delay 20 seconds before booting automaticaly]
   U-Boot> setenv autostart yes                                                                                 [Boot automatically on power-up/reset]
   U-Boot> saveenv
   U-Boot>

[REMIND: Update the above procedure, show two or thee approaches (ip, dhcp, bootp)]

Tailoring your system prior to Booting

There are a few tweaks we mentioned that developers have found convenient to add to the the root file-system before booting. As an initial environment for developing we are suggesting to mounting /home/default and /usr/local files-systems which have a number of files useful for getting started. 

   $ cd /export/hifi-2_home_default
   $ ls -l
   drwxrwxrwx   12 root     root         4096 Dec  1 23:33 Audio_Tests/
   drwxr-xr-x    2 default  default      4096 Oct 28 17:46 Files/
   drwxr-xr-x    6 root     root         4096 Dec  2 02:46 LTP_Test/
   drwxr-xr-x    2 root     root         4096 Nov 20 15:13 Music/
   -rw-r--r--    1 10415    10000         841 Nov 20 01:18 SSH_Keys
   drwxr-xr-x    2 root     root         4096 Nov 13 12:14 Tests/
   drwxr-xr-x    2 10415    10000        4096 Nov 19 23:23 hifitest/
   drwxr-xr-x    5 root     root         4096 Dec  2 05:33 mplayer_packages/
   -rwxr-xr-x    1 10415    10000         544 Dec  2 03:01 save_root_files*
   -rw-r--r--    1 root     root        37888 Dec  2 03:13 saved_root_files.tar


Notice a file tar ball in the /home/default file system called saved_root_files.tar. This is a tar file of files that developers have found convenient to add and replace on the root file system after adding a new buildroot file system. Here is a list of the files and a brief explanation on why it's convenient to add or replace them: 

   root/.bash_profile                                          [added 'ulimit -c unlimited to allow core dumps to be created]
   root/.bashrc
   etc/profile                                                 [added 'ulimit -c unlimited to allow core dumps to be created]                                        
   etc/fstab                                                   [Tells the system how to mount extra NFS file systems like /home/default]
   etc/init.d/S90local                                         [Mounts /home/default]
   etc/resolv.conf                                             [Location of DNS servers when your not using DHCP to boot the kernel]
   etc/TZ                                                      [Your time zone, currently set to California TZ]
   etc/dropbear/dropbear_rsa_host_key                          [Old DropBrer keys, useful if you prefer Dropbear of sshd]
   etc/dropbear/dropbear_dss_host_key                          [Old DropBrer keys, useful if you prefer Dropbear of sshd]
   etc/ssh_config                                              [Typically tailored with things like allowing root logins via ssh]
   etc/ssh_host_dsa_key                                        [sshd keys - Takes 30 minutes to generate, saves time on initial boot]
   etc/ssh_host_dsa_key.pub                                    [sshd keys - Takes 30 minutes to generate, saves time on initial boot]
   etc/ssh_host_key                                            
   etc/ssh_host_key.pub
   etc/ssh_host_rsa_key
   etc/ssh_host_rsa_key.pub
   etc/sshd_config                                             [Typically tailored with things like allowing root logins via ssh]
   etc/rndc.key                                                 
   etc/random-seed                                             [Generated during 1st boot]
   etc/passwd                                                  [Changed default user's shell to bash]
   etc/shadow                                                  [Changed default and root users login password to 'linux1', need to ssh to the board]
   exports/                                                    [The path to where the board can mount extra file systems like /home/default.
   usr/local                                                   [Makes it so /usr/local and be mounted; it has local additions, including /usr/local/src]
   codecs                                                      [NFS partition with Tensilica HiFi-2 Codecs]

Now lets assume your going to stay with mosts of these changes and modify a few of them after tar'ing in these changes to the root file-system. So here we add the tar ball files to the boards root filesystem. 

   $ cd /exports/LINUX_ROOT.HiFi-2
   $ tar xf /exports/hifi-2_home_default/saved_root_files.tar

This is a good time to edit a few files on the boards file system before booting it. 

   $ cd /exports/LINUX_ROOT.HiFi-2
   $ vi etc/resolv.conf                                     [Place your domain information if not using a dhcp boot]
   $ vi etc/fstab                                        [Change fstab entry for boards root filesystem, and others to your taste]
   $ vi etc/init.d/S90local                              [You might want to disable mounting of non-root NFS file systems ...
                                                                ... on the 1st Boot and add this once you try it manually]

Booting Linux for the 1st Time

We should now be ready to boot linux on your LX200. You have exported the root file-system and made the kernel available to a TFTP server. Now let's start with hitting the reset button on the LX200 and it should auto-boot the kernel, resulting in output such as this example log.

Tailoring your system prior to developing for HiFi 2

To make your experience more pleasant we suggest you tailoring your environment. Here are some of the changes that we have found helpful and provided in the saved_root_files: 

  1. Added a root password to that you can login with ssh.
  2. Running rdate with an ntp server on booting.
  3. Adding NFS mounts to /etc/fstab for your code and buildroot code.
  4. Copy in previous ssh server encryption keys to /etc/dropbear to speed up your initial boot.
  5. Mount a 'default' user home directory with:
     a. Linux Test Suite pre-patch to test the system
     b. Audio test example files
     c. Copies of Mplayer and its Plug-in build environment from Buildroot modified slightly to make installation easy.
     d. Misc audio test programs.
  6. Mounting Tensilica HiFi-2 Codecs to easily get mplayer working with HiFi-2 TIE instructions.

Building Linux Applications

Building Linux Applications Using GCC on the Host

You can use the open source toolchain included in the buildroot tree.

Given the location of the buildroot tree and the name of the core: 

  $ setenv BUILDROOT_DIR  /export/src/HiFi-2_DemoBoard/buildroot-xtensa-HiFi2-Snapshot.12
  $ setenv CORENAME       test_mmuhifi_c3

You can either set the PATH and invoke tools prefixed with xtensa_${CORENAME}-linux- : 

  $ setenv PATH   ${BUILDROOT_DIR}/build_xtensa_${CORENAME}/staging_dir/usr/bin:${PATH}
  $ xtensa_test_mmuhifi_c3-linux-gcc -g hello.c -o hello
  $ xtensa_test_mmuhifi_c3-linux-gdb hello

or alternatively invoke the tools with absolute paths: 

  $ ${BUILDROOT_DIR}/build_xtensa_test_mmuhifi_c3/staging_dir/usr/bin/xtensa_test_mmuhifi_c3-linux-gcc -g hello.c -o hello
  $ ${BUILDROOT_DIR}/build_xtensa_test_mmuhifi_c3/staging_dir/usr/bin/xtensa_test_mmuhifi_c3-linux-gdb hello

Building Linux Applications Using GCC on the Target

This is the simplest. (Much slower of course at 45 MHz across a slow Ethernet link than on a workstation, but very convenient.) Just login to the target system and use the native gcc.

Building Linux Applications Using XCC (Xtensa Tools)

There are two approaches to compiling with Tensilica's XCC compiler (part of Xtensa Tools). The normal one, described below, is to initially setup a virtual core that has built-in references to the library and include files for the target Linux system. Alternatively, one could skip this initial setup and just use Xtensa Tools to create object files and link them using host or target GCC tools. However, such objects must be built without dependencies on such things as the C library, which can be harder than it sounds (for example, flags and structures, such as open()'s O_EXCL and stat()'s struct stat, must be avoided because their definitions likely differ between the Xtensa Tools' default C library and the Linux uClibc library). (Note: Codecs such as MP3 and AAC are typically written in C with TIE extensions and can only be compiled with XCC.)


Section 4.3 of the latest Xtensa OSKit Guide (from Tensilica's RC-2009.0 release) describes how to setup XCC to compile Linux applications. For full details, see the guide. A summary follows.

Initial Setup

The XTENSA_TOOLS_ROOT, XTENSA_ROOT, BUILDROOT_DIR, and TARGET_SYSROOT environment variables must be set according to where things were installed; values shown here are for illustration only. The CORENAME variable, set correctly below for this board, reflects the name of the core as known to open source tools (as opposed to XTENSA_CORE which is the core name as known to Xtensa Tools; both happen to match here). 


   $ setenv USER              someuser
   $ setenv XTENSA_ROOT       /home/${USER}/Xplorer/XtDevTools/install/builds/RC-2009.0-linux/test_mmuhifi_c3
   $ setenv XTENSA_TOOLS_ROOT /home/${USER}/Xplorer/XtDevTools/install/tools/RC-2009.0-linux/XtensaTools
   $ setenv TARGET_SYSROOT    /exports/LINUX_ROOT.HiFi-2
   $ setenv BUILDROOT_DIR     /export/src/HiFi-2_DemoBoard/buildroot-xtensa-HiFi2-Snapshot.12
   
   $ setenv CORENAME         test_mmuhifi_c3
   
   $ cd ${BUILDROOT_DIR}
   $ ${XTENSA_ROOT}/xtensa-elf/src/linux/bin/xt-xcc-linux-install                          \
       --sysroot=./build_xtensa_${CORENAME}/staging_dir                                    \
       --linux-gcc=./build_xtensa_${CORENAME}/staging_dir/usr/bin/xtensa_${CORENAME}-linux-gcc

Regular Use

Assuming the above completed successfully, you can now build applications using Xtensa Tools. First set the usual environment variables (assuming values of XTENSA_ROOT and XTENSA_TOOLS_ROOT used earlier): 

   $ setenv XTENSA_CORE      default
   $ setenv XTENSA_SYSTEM    ${XTENSA_ROOT}-linux/config
   $ setenv PATH             ${XTENSA_TOOLS_ROOT}/bin:${PATH}

Now you can use Xtensa Tools to assemble, compile, and link applications for the Linux target specified during setup. For example: 

   $ echo '#include <stdio.h>' > hello.c
   $ echo 'int main() {printf("Hello!\\n");return 0;}' >> hello.c
   $ xt-xcc -g hello.c -o hello

Then copy it where the target can see it: 

   $ cp hello ${TARGET_SYSROOT}/root

And run it on the target: 

   [root@hifi ~]# /root/hello
   Hello!
   [root@hifi ~]#

Here's a more interesting example that uses Tensilica TIE features. (This cannot be compiled using GCC.) 

   $ cd ${TARGET_SYSROOT}/home/default/Audio_Tests
   $ xt-xcc -g hifitest.c -o hifitest

In a ssh termulator window on the board you can now run hifitest: 

   [root@hifi ~]# cd /home/default/Audio_Tests/
   [root@hifi Audio_Tests]# ./hifitest
   cnt:0x0, pid:23178; Eatting cpu; time:0 <control-C>
   
   [root@hifi Audio_Tests]#


Here is the source code for the hifitest.c source file used above.

Limited (No Setup) Use of Xtensa Tools for Linux Targets

Below we illustrate compiling a simple audio test program on a workstation. We start by referring to the XTENSA tools build by Xplorer, putting XCC into our search path and set the standard XTENSA_* environment variables. For example: 

   setenv XTENSA_CORE      test_mmuhifi_c3
   setenv XTENSA_ROOT      /home/pdelaney/Xplorer/XtDevTools/install/builds/RC-2009.0-linux/test_mmuhifi_c3
   setenv XTENSA_SYSTEM    /home/pdelaney/Xplorer/XtDevTools/install/builds/RC-2009.0-linux/test_mmuhifi_c3/config
   setenv XTENSA_TOOLS     /home/pdelaney/Xplorer/XtDevTools/install/tools/RC-2009.0-linux/XtensaTools/bin
    
   setenv PATH ${XTENSA_TOOLS}:${PATH}
   
   
   [piet@fc9desktop Tests]      $ cd /exports/hifi-2_home_default/Audio_Tests                           [NOTE: This is being done on a Workstation]
   [piet@fc9desktop Audio_Tests]$ xt-xcc -g3 -O0 -fPIC -c hifitest.c


Next we link the object on the LX200 board and run gdb on the TIE enhanced code: 

  [root@hifi Audio_Tests]# gcc -g hifitest.o -o hifitest
  [root@hifi Audio_Tests]# ./hifitest
                            cnt:0x0, pid:4640; Eatting cpu; time:0
                            cnt:0x0, pid:4640; Eating Tie; time:7
  ^C
  [root@hifi Audio_Tests]# gdb ./hifitest                                                               [NOTE: This is being done on the LX200 board]
  GNU gdb 6.6
  Copyright (C) 2006 Free Software Foundation, Inc.
  GDB is free software, covered by the GNU General Public License, and you are
  welcome to change it and/or distribute copies of it under certain conditions.
  Type "show copying" to see the conditions.
  There is absolutely no warranty for GDB.  Type "show warranty" for details.
  This GDB was configured as "xtensa_test_mmuhifi_c3-linux-uclibc"...
   Using host libthread_db library "/lib/libthread_db.so.1".
  (gdb) break main
  Breakpoint 1 at 0x400401: file /exports/default/Audio_Tests/hifitest.c, line 20.
  (gdb) run
  Starting program: /home/default/Audio_Tests/hifitest 
   
  Breakpoint 1, main (argc=1, argv=0x3fb3fab4)
      at /exports/default/Audio_Tests/hifitest.c:20
  20	     time_t time0 = time(NULL);
  (gdb) step
  21	  time_t time1 = time(NULL);

Compiling Generic GPL Packages

For your development you may want to add a few GPL packages that you find helpful. This can be done on the LX200 just as you would on a normal workstation, though much slower. For example here we configure and build a few common GPL packages: 

 Building the Strace Package

 Building the vim Package

Compiling the Mplayer Plugins and linking them with MPEG-1 Audio Layer 3 (MP3) and MPEG-4 AAC Codecs

Mplayer is provided as an example environment for developing and testing Codecs and HiFi 2 software. There are two ways to build Mplayer and the plug-in modules that use the codecs. The buildroot tree (pulled with git) has a copy of mplayer and the plugins that can be built in the snapshot via 'make menuconfig'. This is a good environment to use once codecs are developed and debugged.

To facilitate development the mplayer packages can be copied to your NFS mounted development environment. From there you can just configure mplayer to compile on the board and debug mplayer and your codecs with gdb locally.

In the default user home directory we have a directory /home/default/buildroot_mplayer_stuff with a copy of three of the mplayer packages: 


   [root@hifi buildroot_mplayer_stuff]# ls -l
    drwxr-xr-x   34 root     root         4096 Nov 10 05:01 MPlayer-1.0rc2/
    drwxr-xr-x    4 root     root         4096 Nov 10 01:36 mplayer_hifi2_aacplus_v2_plugin/
    drwxr-xr-x    3 root     root         4096 Nov 10 00:57 mplayer_hifi2_mp3_plugin/

they were simply copied from the buildroot-xtensa-HiFi2-Snapshot.2/package directory.

To get your development environment ready to compile the mplayer plug-ins you need to configure Mplayer to use the local C compiler and linker: 

   # cd /home/default/buildroot_mplayer_stuff/MPlayer-1.0rc2/
   # CFLAGS="-g3" ./configure

This will take about 15 minutes to configure. After that you can build the plugins or mplayer. If you want to recompile mplayer it's likely best/necessary to use the same args to .configure as used by buildroot: 

       .CFLAGS="-g3" ./configure \
               --prefix=/usr \
               --confdir=/etc/mplayer \
               --with-extraincdir=/usr/include \
               --with-extralibdir=/lib \
               --disable-gui \
               --enable-mad \
               --enable-fbdev \
               --disable-mencoder \
               --disable-dvdnav \
               --disable-dvdread \
               --disable-dvdread-internal \
               --disable-libdvdcss-internal \
               --disable-big-endian \
               --disable-nemesi \
               --disable-tv \
               --enable-dynamic-plugins

We are currently able to compile mplayer on the LX200 but due to space limitations it's not possible to compile it -O0.


Now, let's focus on compiling linking the plugins. They are a nice example of compiling an audio application on the LX200.

We modified the plugin Makefile slightly, and they are available in /home/default/mplayer_packages. These additions just instruct make how to fetch the codecs and build and install the plugins as explained in the Chapter 7 of the Linux HiFi application note. With these Makefile additions and the Tensilica codecs available in the /plugins directory is very easy.

For example the mp3 plugin has this addition: 


   # We assume Tensilica Codecs have been mounted at /codecs
   # via /etc/fstab during boot.
   #
   CODEC_PACKAGE=xa_hifi2_l32r_LE5_pic_mp3_dec_lib_3_1_api_1_15_lib
   CODEC_PACKAGE_LOCATION=/codecs
   MPLAYER_DEVEL_LOCATION=/home/default/buildroot_mplayer_stuff
    
   all: $(XA_CODEC_NAME) $(SLIBNAME) $(XA_CODEC_NAME).so
   .
   .
   .
   $(CODEC_PACKAGE).tgz:
           cp $(CODEC_PACKAGE_LOCATION)/$(CODEC_PACKAGE).tgz .
   
   $(CODEC_PACKAGE).tar:: $(CODEC_PACKAGE).tgz
           gunzip $(CODEC_PACKAGE).tgz
   
   $(XA_CODEC_NAME):: $(CODEC_PACKAGE).tar
             tar xf $(CODEC_PACKAGE).tar
   
   install::
           @-mkdir /etc/mplayer
           cp codecs.conf /etc/mplayer
           @-mkdir /usr/lib/mplayer
           cp ad_xa_mp3_dec.so /usr/lib/mplayer/
           cp xa_mp3_dec.so /usr/lib/mplayer
           chmod 755 /usr/lib/mplayer/ad_xa_mp3_dec.so
           chmod 755 /usr/lib/mplayer/xa_mp3_dec.so


The make file will be just providing a codec config file for mplayer at /etc/mplayer/codecs.conf and copying the plug-in to /usr/lib/mplayer. To install the mp3 codec plugin and mplayer config file just copy your codec that was compiled with xcc to the directory, compile it, and install. To add mp3 and aac plugins to mplayer you just type make followed by make install: 

   [root@hifi mplayer_hifi2_mp3_plugin]# make
   cp /codecs/xa_hifi2_l32r_LE5_pic_mp3_dec_lib_3_1_api_1_15_lib.tgz .
   gunzip xa_hifi2_l32r_LE5_pic_mp3_dec_lib_3_1_api_1_15_lib.tgz
   tar xf xa_hifi2_l32r_LE5_pic_mp3_dec_lib_3_1_api_1_15_lib.tar
   cc -I../libavcodec -I../libavformat -I. -I.. -I../libavutil -W -Wall -O2   -pipe -g3  -D_REENTRANT -DHAVE_CONFIG_H -I/usr/include  -DNDEBUG -fvisibility=hidden -Ixa_mp3_dec/include -I../MPlayer-1.0rc2 -Ic
   xa_mp3_dec_sample_testbench.c: In function 'xa_mp3_decode_frame':
   xa_mp3_dec_sample_testbench.c:185: warning: pointer targets in passing argument 1 of 'xa_mp3_audio_read' differ in signedness
   xa_mp3_dec_sample_testbench.c:163: warning: unused variable 'j'
   xa_mp3_dec_sample_testbench.c: In function 'mp3_codec_init':
   xa_mp3_dec_sample_testbench.c:517: warning: pointer targets in passing argument 1 of 'xa_mp3_audio_read' differ in signedness
   xa_mp3_dec_sample_testbench.c: At top level:
   xa_mp3_dec_sample_testbench.c:112: warning: 'pack_32_to_24_bits' defined but not used
   cc -I../libavcodec -I../libavformat -I. -I.. -I../libavutil -W -Wall -O2   -pipe -g3  -D_REENTRANT -DHAVE_CONFIG_H -I/usr/include  -DNDEBUG -fvisibility=hidden -Ixa_mp3_dec/include -I../MPlayer-1.0rc2 -Ic
   ad_xa_mp3_dec.c: In function 'xa_mp3_audio_read':
   ad_xa_mp3_dec.c:26: warning: pointer targets in passing argument 2 of 'demux_read_data' differ in signedness
   ad_xa_mp3_dec.c: In function 'init':
   ad_xa_mp3_dec.c:42: warning: pointer targets in passing argument 1 of 'xa_mp3_decode_frame' differ in signedness
   ad_xa_mp3_dec.c: At top level:
   ad_xa_mp3_dec.c:52: warning: unused parameter 'sh'
   ad_xa_mp3_dec.c:56: warning: unused parameter 'arg'
   ad_xa_mp3_dec.c:78: warning: unused parameter 'sh_audio'
   cc -I../libavcodec -I../libavformat -I. -I.. -I../libavutil -W -Wall -O2   -pipe -g3  -D_REENTRANT -DHAVE_CONFIG_H -I/usr/include  -DNDEBUG -fvisibility=hidden -Ixa_mp3_dec/include -I../MPlayer-1.0rc2 -Im
   cc -I../libavcodec -I../libavformat -I. -I.. -I../libavutil -W -Wall -O2   -pipe -g3  -D_REENTRANT -DHAVE_CONFIG_H -I/usr/include  -DNDEBUG -fvisibility=hidden -Ixa_mp3_dec/include -I../MPlayer-1.0rc2 -Ie
   [root@hifi mplayer_hifi2_mp3_plugin]#

   [root@hifi mplayer_hifi2_mp3_plugin]# make install
   mkdir: cannot create directory '/etc/mplayer': File exists
   make: [install] Error 1 (ignored)
   cp codecs.conf /etc/mplayer
   mkdir: cannot create directory '/usr/lib/mplayer': File exists
   make: [install] Error 1 (ignored)
   cp ad_xa_mp3_dec.so /usr/lib/mplayer/
   cp xa_mp3_dec.so /usr/lib/mplayer
   chmod 755 /usr/lib/mplayer/ad_xa_mp3_dec.so
   chmod 755 /usr/lib/mplayer/xa_mp3_dec.so
   [root@hifi mplayer_hifi2_mp3_plugin]#


The unpacking of the Tensilica mp3 codec tarball will installed the following files: 

   xa_mp3_dec/
   xa_mp3_dec/README
   xa_mp3_dec/include/
   xa_mp3_dec/include/mp3_dec/
   xa_mp3_dec/include/mp3_dec/xa_mp3_dec_api.h
   xa_mp3_dec/include/xa_apicmd_standards.h
   xa_mp3_dec/include/xa_error_handler.h
   xa_mp3_dec/include/xa_error_standards.h
   xa_mp3_dec/include/xa_memory_standards.h
   xa_mp3_dec/include/xa_type_def.h
   xa_mp3_dec/test/
   xa_mp3_dec/test/build/
   xa_mp3_dec/test/build/ldscript_stream_data.txt
   xa_mp3_dec/test/build/makefile_testbench_sample
   xa_mp3_dec/test/build/paramfilesimple.txt
   xa_mp3_dec/test/include/
   xa_mp3_dec/test/include/id3_tag_decode.h
   xa_mp3_dec/test/src/
   xa_mp3_dec/test/src/xa_mp3_dec_sample_testbench.c
   xa_mp3_dec/test/src/id3_tag_decode.c
   xa_mp3_dec/test/src/stream_data.c
   xa_mp3_dec/test/src/xa_mp3_dec_error_handler.c
   xa_mp3_dec/test/test_inp/
   xa_mp3_dec/test/test_inp/compl.mp3
   xa_mp3_dec/test/test_inp/hihat.mp3
   xa_mp3_dec/test/test_out/
   xa_mp3_dec/test/test_out/force_mkdir.txt
   xa_mp3_dec/test/test_ref/
   xa_mp3_dec/test/test_ref/compl_24bit.wav
   xa_mp3_dec/test/test_ref/hihat_16bit.wav
   xa_mp3_dec/lib/
   xa_mp3_dec/lib/xa_mp3_dec.a
   xa_mp3_dec/doc/
   xa_mp3_dec/doc/HiFi2-MP3-DecoderProgrammersGuide.pdf


[TO BE DONE - Add missing C file, make clean deletes it!]

The xa_mp3_dec.a archive will be used by the Makefile in the mplayer_hifi2_mp3_plugin directory to make the mplayer plug-in. Section 6 of the 'Using Tensilica HiFi 2 Codec on Xtensa Linux with MPlayer Application Note has a detailed description of the encapsulation process used by the plug-ins.

Adding a Codec to Buildroot

Xtensa developers provide detailed instructions on building the root filesystem and the Linux kernel.

Building a comprehensive development environment with buildroot can be a challenging experience and worthy of providing some tips on process. Here are notes of the configs used for the three menuconfigs in this 2nd snapshot provided with SMP additions: 

    $ make  menuconfig
    $ make  uclibc-menuconfig
    $ make  busybox-menuconfig

[TO BE DONE - making a new tar ball of saved files, building buildroot, ...]

Known Problems being investigated, suggested that you know about and possibly avoid

 1. Using NFS mounts with default parameters causes memory congestion. Use these mount options:
     
     vers=2,rsize=4096,wsize=4096,hard,nointr,nolock,nolock,timeo=11,retrans=3,noauto
   
    this is extremely important to add to your /etc/fstab on the target.
    
 2. Can't swap over NFS yet, memory can get tight and cause application to be killed.
   a. Trying procedure documented in U-Boot Manual.
 
 3. Building the C development with X11 doesn't work with buildroot.
  
 4. Though Mplayer plug-in can be compiled, Mplayer can be compiled but still has a few issues:
   a. Can't be compiled -O0 due to limited memory while compiling one file,
   b. Compiler infrequently crashes and make has to be restarted.
      Not seeing this problem with root build on Fedore Core 9.
      Perhaps this was caused by debug kernel or LTP using all of the memory.
  
 5. U-boot has flash problems:
   a. Sectors marked Read-Only come up Writeable after a reset/reboot.
   b. Flashing a large number of sectors (like the kernel) sometimes
      results in an Error (Ex: Vcc) and had to be retried.
   c. Saw environment variables trashed on reset/reboot once.
      It's possible that U-boot in flash could get whacked
      and the board will need to be re-flashed. During a week
      or two of testing I haven't see environment getting whacked.
    
 6. gdb appears to be crashing on target when debugging 
    on latest root with uclibc left unstriped and with debug;
    core dump sent to maxim.
     
 7. U-Boot seems to hang periodically when loading the kernel with
    tftp; appears to be worse when network activity is high.
  
 8. 'top' command only shows all cpu's or cpu0; cpu 1 and 2 missing.
              
 9. Program dore dump require ulimit -c to be set but root uses /bin/sh
    which is a link to bash but causes it to skip running the bash
    startup scripts. Changing root to /bin/bash seems to mess up
    ssh logins.
   
 10. For kernel to be compiled on the LX200 (for self checking:
     a. Xtensa makefile needs to be fixed:
          CC      init/do_mounts.o
          LD      init/mounts.o
        /bin/sh: xtensa_test_mmuhifi_c3-linux-uclibc-ld: command not found
        make[1]: *** [init/mounts.o] Error 127
      
     b. Need to add ncurses-devel package for 'make menuconfig'
  
   
 11. busybox vesion of vi doesn't work very good, use /usr/local/bin/vi.
      /usr/local/bin search first in bash profile and rc.

Further reading

Main Xtensa Linux resources are:

Thanks to

  • piet
  • marc
  • dan

And the rest of the people in the Linux-Xtensa mailing list, if you cannot go through some of the steps, don't hesitate to ask on the mailing list, there's always somebody willing to help you!

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