Re: [Ltib] LTIB for Raspberry Pi

[Stuart Hughes]

Hi Sean,

My apologies in advance, these days I have very little time to devote to this project.

Anyhow, having said that I've attached an html rendering of a note you will find under 'doc' in the LTIB CVS distribution.  It describes in principle how to add a new platform.  Note that the section about the toolchain will work, but is not how most platforms are handled these days (they use toolchains.lkc).

Fundamentally, what you need is:

• A working pre-compiled cross toolchain that is compatible with LTIB (that used to mean CodeSourcery style toolchains from the 2004 era).
• A kernel.spec file. Actually you just need the fragment that referecnes your kernel sources.  See config/platform/ep93xx/kernel-2.6.15-ep93xx.spec.in for an example.  .spec files can go in you platform directory (as in this example) or if common to more than one platform under dist/lfs-5.1/xxx
• A platform defconfig (described in the note).

Sorry to be so brief, but take a look at this note, and the others in the doc directory and have a scan of the FAQ at http://ltib.org/documentation-LtibFaq and see how you get on.  There are others on this list who have also been through this who may be able to help.

Regards, Stuart

On 16/09/12 06:02, Malloy, Sean C. wrote:

I've made a successful first pass at LTIB for the Raspberry Pi and was wondering how much more actual work was in front of me if I wanted my config added to the official list of platforms. 

As of now, what I have working is this:

Kernel 3.2.27-cutdown is your only choice for a kernel, and it builds from local source.  I should download kernels from the RasPi sites during the build...

I built my own custom toolchain using ct-ng and glibc.  Support for uClibc needs to be verified.  And perhaps an official toolchain for RPi should be selected or built. 

As of right now, I have to copy images to the SD card manually as the RPi wants /boot on partition 1 as FAT, and the rootfs on partition 2 as ext4, though the type is configurable.   I'm sure there's a way to automate this, but I haven't found it yet.  (RPi doesn't use a real boot loader, but instead boots the GPU, who then acts as a boot loader for the CPU.  Apparently the GPU binary is closed source.)

Busybox is being used as init.  Currently, if Busybox is dynamically linked, I get the dreaded "no init found" Panic message on boot.   If staticly linked, I boot to a login prompt.   This is odd because I was able to run a dynamically linked hello world program as /sbin/init successfully.   I'll get this figured out eventually. 

So, in this basic configuration, top shows a memory usage of just 4.5M in a not-very-optimized setup, without X. 

If there's enough interest in adding RPi support to LTIB, I'll be happy to share so long as I can get some guidance as to what I need to do in order to get it ready for prime time. 


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LtibCreateNewTarget

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Copyright © Freescale Semiconductor, Inc. 2004-2005. All rights reserved.

Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.2
or any later version published by the Free Software Foundation;
with no Invariant Sections, no Front-Cover Texts, and no Back-Cover
Texts.  A copy of the license is included in the file doc/COPYING

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How to add a new target platform to LTIB

This is a quick HOWTO that will show how to add a new target platform into LTIB.

For the purposes of this tutorial, an existing mpc8555cds is used as the
template for a new mpc5200 target.

This tutorial assumes that you are working using the latest cvs HEAD for LTIB.

What you should have available before you start

• A working cross toolchain for your target. Many are already available in the toolchain foundry and show in existing LTIB targets.

• Kernel source and a kernel .config file for your target.

• If required, bootloader source for your target.

Create a placeholder for the new target BSP

To do this copy an existing target for later editing.  This will serve as
a template for the new target.

You should use an existing target that is the closest match for your new
target.

cd ~/ltib/config/platform
cp -a mpc8555cds mpc5200
rm -rf mpc5200/CVS

Update the main.lkc file for your platform.

The main things you need to change are:

Platform information

You need to check and update the following as required:

CONFIG_TITLE	This is the name that shows up at the top of the LTIB config menu
PLATFORM_COMMENT	This is similar to CONFIG_TITLE, this shows up in the platform selection menu when you first run LTIB.
VENDOR	This should be set to the board's vendor name
PLATFORM	This should exactly match the directory name of this platform (e.g. mpc5200)
GNUTARCH	This is the GNU architecture name for this target (e.g. powerpc)
LINTARCH	This is the Linux architecture name for this target (e.g. ppc)
CFGHOST	This is the name that configure should use for the --host entry when running configure for a package (e.g. powerpc-linux)

Set these to be appropriate for your platform.

Capabilities section

This can normally be left (empty).  The defaults come from 
config/userspace/defaults.lkc.  The sorts of things that you may need
to change are ERASE_BLOCK_SIZE for instance, if your Flash erase blocks
are not 64KB.

Toolchain selection

Look at and update the toolchains as appropriate.  There should be at 
least 2 choices:

TOOLCHAIN1	(something from the toolchain foundry, see: http://twiki.freescale.net/bin/view.cgi/MWERKS/ToolchainFoundry)
TOOLCHAIN_CUSTOM	this is used to select customer toolchains

You need to put in corresponding defaults for TOOLCHAIN1 in the following areas:

TOOLCHAIN	selects the toolchain's x86 rpm filename. e.g. mtwk-lnx-powerpc-603e-gcc-3.3.2-glibc-2.3.2-0.28-6.i686.rpm
TOOLCHAIN_PATH	the install path to the toolchain, minus the /bin. e.g. /opt/mtwk/usr/local/powerpc-603e-linux/gcc-3.3.2-glibc-2.3.2
TOOLCHAIN_PREFIX	the cross compiler prefix. e.g. powerpc-603e-linux-
TOOLCHAIN_CFLAGS	any mandatory CFLAGS that must be used with your chosen cross compiler. These should be conditioned per toolchain. e.g. default "xxxx" if TOOLCHAINn

Bootloader selection

This is optional, but if you have a bootloader you want built, adjust 
this area appropriately.

Kernel selection

There should be at least 2 entries:

KERNEL1	a description of your for the target. e.g. "Linux 2.6.11.7 for MPCLite5200B (from PCS BSP)"
KERNEL_NONE	this entry is so you can disable kernel building

You need to put the corresponding defaults for KERNEL1:

PKG_KERNEL	the name of the specfile to build this kernel, without the .spec extension. e.g. default "kernel-2.6.11-mpclite5200b" if KERNEL1
PKG_KERNEL_PRECONFIG	the filename of the kernel config file to be used with your specfile. This should reside in the directory 'config/platform/. e.g. default "linux-2.6.11-mpclite5200b.config" if KERNEL1

Add any new spec files

If your main.lkc refers to any new spec files, you need to add them in 
to the directory: dist/lfs-5.1/

(e.g. package may be kernel, u-boot etc).

Configure your ltib config file.

Run:

./ltib --configure

This will configure your platform based on the settings of the one you've copied. Make adjustments as required. When you save and exit, a '.config' file will be saved in your platform's directory and ltib will build this configuration. When you are done, copy the .config to defconfig in your platform's directory e.g:

cp config/platform/mpc5200/.config config/platform/mpc5200/defconfig

Saving your work.

Once you have a default config you are happy with and your platform builds and boot, you need to commit the new files to LTIB's CVS and copy any sources to the GPP. To save files to the GPP, use the link 'Upload a file to the GPP' http://www.bitshrine.org/cgi-bin/gpp_upload.cgi. Note: you need to be a project member to do this. Otherwise, please submit your patches to the public mailing list.

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