[Elphel-support] NFS Needed for Dev

[Andrey Filippov]

On Thu, Nov 18, 2010 at 12:32 PM, Rock <rock at peppa.com> wrote:

> On Thu, Nov 18, 2010 at 07:56:15PM +0100, Sebastian Pichelhofer wrote:
> > What do you mean?
> >
> > A firmware upgrade overwrites the entire camera internal file system.
>
>   I don't understand the distinction you are making between an upgrade and
> firmware upgrade. If everything is a file in the normal Elphel setup then
> thats fine. But I have some questions:
>
>  * How does the boot-loader work for example?
>

The start of the boot-loading is the same as for any Axis ETRAX FS systems,
more information should be in their site. But basically the first is the ROM
bootloader of the ETRAX (proprietary, closed-source, unmodifiable), it
determines one of the few boot modes by probing the I/O pins. In the 10353
there are only 2 modes used  - NAND Flash and network. The modes are
selected by plugging/unplugging of the network cable. Originally we used a
normal button, but it caused problems reflashing if you do not have physical
access to the camera; unplugging can be done on the other end of the cable.
Next step - loading of the second level bootloader (the one that is
compiled) - it is done from the page 0 of the flash (or over the network).
The page 0 also has stored the MAC address, manufacturing timestamp, camera
model and revision of the system board. This information is not not normally
overwritten - reflashing erases/overwrites everything but this page zero. Of
course it is still possible to erase and overwrite that page, but we had to
implement a little of the "security through obscurity" here - when we had
just 2 scripts (modified from those from Axis) "flashit" (all but page0)
tand "flashitall" (all, including page0) many of our users ran flashitall
script instead of the flashit "just in case", erasing the timestamps and
serial numbers.

Next stage - loading compressed Linux kernel and the root file system from
one of the flash JFFS partitions (it stays readonly).



>  * What if I want to boot a variety of kernels?
>

No special support, When I'm working on the drivers, I rebuild the software
and reflash the camera. BTW, if you have recommended KDevelop3 installed,
selecting "compile" having the driver source open re-build the kernel,
having application - builds and installs (under target/) the application
that you can ftp to the camera, selecting "build project" - creates the
complete camera flash image.


>  * Can I boot with a special kernel option?
>

get to the top installation directory, run
. ./init_env
cd /os/linux
make menuconfig
and then run make install from the top directory

You may also modify the elphel353/kernelconfig-2.6


 * How do I upgrade my kernel and modules if needed?
>

Upgrading kernel (it is 2.6.19 now) would be rather difficult - there are
multiple modifications by Axis itself and as they discontinue the processor
that development is probably over. But we even did not upgrade to the very
latest version of Axis SDK - there are too many of our modifications on top
of that. So the latest kernels will only be available with the next 373,
that was put aside during the Eyesis development.


>  * Where are the special boot files?
>
What files exactly?


>  * Where do the FPGA files live?
>
/etc/x353.bit
/etc/init.d/fpga - script that loads the FPGA and does many other
camera-specific initialization. Loading the FPGA image itself is just "cat"
bitfile to the appropriate fpga driver

 * Is there an overview of the Elphel file system?
>

Probably not. there is some information here and there, So if somebody could
start such on the wiki - we can probably make it together


>  * Is there an overview of the boot process for the non-linux embedded
> BIOS?
>

The boot process is mostly similar to what we got from Axis, so there should
be documentation there.

>
>  I'm looking for an overview of files so I don't have to go through a live
>  system and find every piece the hard way. I know my way around linux, but
>  every embedded system is different.
>
>
Yes, sure, but we do not have the complete documentation. If you write more
of the specific questions, description of what you are trying to achieve -
we may be able to help with that.

Andrey


>  Thanks,
>
> --------------------------------------------------
> Rock
>
>
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