[PATCH 3/16] Renamed BBB template linker scripts, updated architecture header file, Makefile, config.h

Ed Sutter ed.sutter at alcatel-lucent.com
Wed Jun 17 16:52:33 UTC 2015

One other thing I just noticed (still related to the blog)...

This is a big one actually, so I wanna make sure you understand this.

The umonBssInit() function assumes that the memory it is initializing
is already configured.  This means if you want to use DDR3 as uMon's
BSS space you need to configure it somewhere in rom_reset.S
(prior to any code that actually uses it).
Note, there is a difference between "configure" and "init" here...
In this context, "configure" means you program the CPU's DDR
controller to deal with the physical memory that is attached to it.
Then "init" simply means that we clear the content to be zero.

So, to keep things simple (at least until you get DDR3 initialized clean), I
would just map all of uMon (both rom and ram) to reside in the internal
SRAM of the CPU.   Then you can use the DM and PM commands at the
console prompt to test your DDR3 initialization.
Know what I mean?
> Hello Ed,
> Your Git terminology is spot on. :-)
> I cloned the source tree from the RTEMS git repositories.  The Umon
> source tree that I worked off of was cloned from
> https://git.rtems.org/umon/.
> Please let me know if you have any questions, comments, or concerns in
> regards to cloning Umon.
> I am finishing up patches 4/16 to 16/16.  These patches simply include
> various modifications/additions to get the BBB directory looking more
> like a BBB directory.  I will be submitting them very shortly.
> Hopefully these patches come out all right because to be honest this
> is actually my first time preparing and submitting patches.  If there
> are any discrepancies, please do let me know along with any
> suggestions on how I can resolve the issue.
> Just FYI, I created a blog post documenting how I was approaching the
> porting process.  It can be found here
> http://www.jariellecatbagan.com/the-approach-to-porting-umon-to-the-bbb/.
> Just as before, please let me know if there are any discrepancies.
> As of right now, I am simultaneously preparing the remaining patches
> while working on implementing the DDR3 initialization.  I have also
> created a blog post regarding the fundamentals of DDR3 and what it
> entails to configure it for use on the AM335x/BBB.  The blog post that
> I created can be found here
> http://www.jariellecatbagan.com/the-theory-behind-external-ddr3-initialization-on-the-bbb/.
> I just want to ask what do you think about my thought-process.  Am I
> approaching the porting process in the right direction?
> Thank you.
> Best Regards.
> On Wed, Jun 17, 2015 at 5:08 AM, Ed Sutter <ed.sutter at alcatel-lucent.com> wrote:
>> On 6/17/2015 4:51 AM, Jarielle Catbagan wrote:
>>> Please excuse me if I might have caused any confusion regarding the
>>> order of the patches.  The first two submitted, with the first patch
>>> still waiting for approval to be submitted into this mailing list at
>>> the time of this patch's submission, are [PATCH 1/16] and [PATCH
>>> 2/16].
>>> The template linker scripts were renamed to correspond to the PLATFORM
>>> variable in the BBB Makefile.  The architecture header file was
>>> renamed to relate to the BBB platform.
>>> Modified the CPU type supplied to the -mcpu compiler switch to cortex-a8.
>>> Updated the ROM length that can be potentially allocated to Umon
>>> during the initial boot.  This is done through the modification of
>>> BOOTROMLEN in the Makefile.  The value assigned reflects the fact that
>>> there are 109KB that can be used by Umon during the initial boot
>>> procedures.
>>> Modified the DEFAULT_ETHERADD in config.h to match the MAC addresses
>>> associated with the MAC address of the BBB's that I have.  This value
>>> should be updated on a user-by-user basis.
>> Jarielle,
>> Good stuff...
>> Now I need to play catchup.
>> I had been working with my own local copy of the bbb port, so I need to sync
>> up
>> with you and the repository.  Last I recall, there was confusion regarding
>> where
>> to grab the code from.  Where are you cloning your tree from?
>> Sorry if my "git terminology" is off, I'm still a relatively new user of git
>> (moving off svn
>> slowly but surely).
>> Ed
>> --
>> Ed Sutter
>> Alcatel-Lucent Technologies -- Bell Laboratories
>> Phone: 908-582-2351
>> Email: ed.sutter at alcatel-lucent.com
>> _______________________________________________
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>> umon-devel at rtems.org
>> http://lists.rtems.org/mailman/listinfo/umon-devel
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Ed Sutter
Alcatel-Lucent Technologies -- Bell Laboratories
Phone: 908-582-2351
Email: ed.sutter at alcatel-lucent.com

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