Subject: Problems booting Linux kernel on Sigma SMP8634 #2

From: Andi <[email-masked]>
Date: Wed, 05 Mar 2008 13:35:20 +0100

Hey folks,

first of all, sorry for _waisting_ the list with that topic again and again!

this question is related to that one here, posted sooner on this list:
http://www.linux-mips.org/archives/linux-mips/2008-02/msg00032.html

I spent a bit more time on this topic and found out that there is
seriously something going wrong with memory initialization and/or
handling during Linux startup.

I simply add "mem=32m" to the kernel command line, and the kernel runs
longer, at least a bit. However, it than stops with nearly the same
issue: Unable to handle kernel paging request at virtual address, but
different addresses. Tried "16m, 64m" and other values, all behave in
different way. Resulting to a crash at the position w/o any parameter or
 a bit later on.

Since I am not so familiar MIPS and especially the fact that our hard-
and software is more than closed, I am asking you guys to point me where
to spend more time on in order to get this issue fixed and fire up a
kernel on this box.

I am sure there some more guys around using the smp8634. Is it necessary
to load the microcode in order to get the kernel starting up?
Maybe we don't need the audio/video-ucode but irq-handler-ucode looks
very usefull ;-) Do we just have to copy this code at a certain memory
address?

Thank you in advance ...

Regards,
	Andi

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From: David Daney <[email-masked]>
Date: Wed, 05 Mar 2008 09:03:14 -0800

> to spend more time on in order to get this issue fixed and fire up a

I build and successfully run kernels on the 8634 every day, so I don't 
think it is a problem with the 8634 port in general.

You should probably ask for technical support from whomever supplied 
your hardware.  They would know the technical details about how to 
configure the memory controller, the amount and location of the RAM on 
the board, etc.

> 
> I am sure there some more guys around using the smp8634.

Likely there are.  It is used in many blu-ray disk players, among other 
things.

> Is it necessary

No.

> very usefull ;-) Do we just have to copy this code at a certain memory

N/A, the kernel does not rely on any microcode.

The drivers for the audio/video handling hardware on the 8634 do require 
  microcode, but in many cases it is loaded after the kernel is running. 
  But the microcode is not needed for just running a bare bones kernel.

David Daney

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From: Andi <[email-masked]>
Date: Wed, 05 Mar 2008 19:25:16 +0100

Hi,

> configure the memory controller, the amount and location of the RAM on

Thats right. And I would really like to do so. But unfortunately there
is not much information around about the hardware. Since the box
originally runs a wince system, this project is more like a _free time_
projects of some Linux enthusiasts.

You can get a overview about this here: http://www.t-hack.com/wiki/
There is also a forum, but unfortunately most posts are in German ..

> Likely there are.  It is used in many blu-ray disk players, among other

Ok, there is not much information about the smp8634 out there, which is
really a pity. I know that Sigma is not really interested in publishing
there specifications. Even the gpl part is not published, but I am sure
you already know this :-)

Do you know how to get some more detailed information about the smp8634?

Ok, there are some parts that are not equal, like memory and flash! But
this is a SoC, so most parts are the same.

> N/A, the kernel does not rely on any microcode.

Ok, thanks, so we can cancel this on our todo-list ..

Regards,
	Andi

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From: Andi <[email-masked]>
Date: Thu, 13 Mar 2008 11:11:17 +0100

Hi,

in reply to myself, just in case its useful for somebody else ..
There seems to be a memory limitation for Linux running on the SMP8634!
While giving Linux access to not more than half of the total RAM minus
some (4?) MB the kernel works pretty well!

And even more interesting: one can download the smp8634 kernel sources
for Sony devices on their support pages.

Cheers,
	Andi