Re: [Ltib] LTIB for Raspberry Pi

[Mike Goins]

On Sun, Sep 16, 2012 at 1:02 AM, Malloy, Sean C. <address@hidden> 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.

There is a pre-built at https://github.com/raspberrypi/tools and it
appears to contain three toolchains: soft and hard float, not sure
what the third one is.   They were built using crosstool-ng, which I
have used, but not with ltib.  If crosstool-ng makes toolchains in the
same layout as its inspiration, kegel's crosstool (which does work
well with ltib), then it should not be an issue.

I would take those toolchain sets and split them up into three rpms
using rpmbuild.  That way users get the choice of selecting hard/soft
float in ltib and ltib could carry that setting into the rest of ltib
for building supporting libs.  The drawback is that someone may need
to re-build and version rpms from those toolchain updates.

That method is kind of like adding two (or three) platforms to ltib
instead of one.


> 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.)

Not a real bootloader, as no way to get the RPi to tftp the kernel and
nfs/ramfs boot without the SD card?  If this was possible, then it
could be easily scriptable from within the system after boot.


> 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.

The only thing I could think of is the location of the libraries.  How
about trying 'init=/bin/sh" as a test.


> 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.


I'm in.  Now I have an excuse to buy one.


>
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