Hey,
Any tips for a new guy? I just about ready to start trying to port
linux to our custom MPC850 board.
This is where I stand right now. I have at my disposal a MBX860
which I have managed to get linuxPPC to boot on. I have a copy of Hard Hat
Linux Journeyman Edition. I also have an EST VisionICE in circuit emulator.
Now for the questions.
1. Is there a FAQ or Doc on porting the kernel to a new design? (please mail
or direct me to it)
2. Does anyone know if Hard Hat has any problems with Mandrake 7.0 linux?
3. What do I need to do in the ROM before jumping to HEAD.S other than
programming the ram timmings in the UPM( I assume HEAD.S is where everything
starts )?
4. Has any one managed to get an EST VisionICE in circuit emulator to work
with linuxPPc? If so How? Would I be better off using the GNU Debuger?
Many many thanks if you can answer any of these questions for me.
Conn Clark
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Hi Conn,
I'll have a shot at the ones I know about:
clark@esteem.com writes:
Any tips for a new guy? I just about ready to start trying to port
linux to our custom MPC850 board.
You mentioned head.S; you shouldn't need to modify it at all. We didn't on our
custom 855T design.
1. Is there a FAQ or Doc on porting the kernel to a new design? (please mail
or direct me to it)
There's the HOWTO at:
http://members.xoom.com/greyhams/linux/PowerPC-Embedded-HOWTO.html
...3. What do I need to do in the ROM before jumping to HEAD.S other than
programming the ram timmings in the UPM( I assume HEAD.S is where everything
starts )?
I suggest porting PPCBOOT to it rather than starting from scratch yourself.
See:
http://ppcboot.sourceforge.net/
Regards,
Graham
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clark@esteem.com wrote:
4. Has any one managed to get an EST VisionICE in circuit emulator to work
with linuxPPc? If so How? Would I be better off using the GNU Debuger?
We did use EST's VisionICE box to download linux kernel images to our target
hardware before we had a rom monitor with network loading. It was also helpful
to debug the early boot stuff when we were porting to custom hardware - before
the memory management is enabled. Once the memory manager is enabled, the
VisionICE becomes mostly useless, because as has been said many times on this
list - most BDM debuggers don't understand virtual addresses. Nevertheless the
VisionICE did offer some utility to us.
I wrote a little app that slaps an EST .bin file header on a linux image
(zvmlinux or zvmlinux.inird). I can send that to you if you want it. Then I use
Download to Target from VisionClick and that sticks the whole image in RAM. You
do need to disable VisionICE's interception of software breakpoint emulation
interrupts - do 'cf sbe special'. That should be it.
--
-------------------------------------------------------
Steven K. Rossi srossi@ccrl.mot.com
Staff Engineer
Multimedia Communications Research Laboratory
Motorola Labs
-------------------------------------------------------
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clark@esteem.com wrote:
3. What do I need to do in the ROM before jumping to HEAD.S other than
programming the ram timmings in the UPM( I assume HEAD.S is where everything
starts )?
My startup code at 0xFFF00100 simply loads values into r3-r7 and then
jumps to physical address 0 (where vmlinux was loaded). But our hardware
is initialized from the host, not the on-board CPUs.
4. Has any one managed to get an EST VisionICE in circuit emulator to work
with linuxPPc? If so How? Would I be better off using the GNU Debuger?
I never figured out how to use any of that stuff. I debugged head.S
by using r11 and r12 (otherwise unused) to poke cookies into low
memory, and traced through head.S until it took off (:-)). But my
architecture may be different from yours -- I have a PPC board which
plugs into a host which can read/write the on-board RAM via the PCI
bus. So I could always dump memory on the board.
I had to develop custom console and network drivers using that PCI
memory-to-memory interface. I debugged them using our proprietary OS,
so once I threaded through head.S it was a short trip to a bash console
prompt. Once you get to start_kernel() I doubt any debugger will be of
much use (gdb perhaps, because it understands memory mapping, but the
ICE won't).
Several people have said "don't change head.S". I found I had to,
because my board is not anything like any of the CONFIG choices.
I did, at least, move it into my private directory and symlink it
back where it belongs; ditto for the half-dozen other files I had
to change.
Tom Roberts tjroberts@lucent.com
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