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by k2tom
Wed Apr 20, 2016 5:34 pm
Forum: Bare metal, Assembly language
Topic: RPi2 and kernel_old=1 (bare metal)
Replies: 1
Views: 616

Re: RPi2 and kernel_old=1 (bare metal)

Sorry...

Once I added "core_freq=250" to config.txt, everything worked fine!

I was under the impression (?) that for the RPi3B the (default) core_freq is 400 MHz.. and I had the Mini-UART AUX_MU_BAUD register set accordingly.

Tom
by k2tom
Mon Apr 18, 2016 3:16 pm
Forum: Bare metal, Assembly language
Topic: RPi2 and kernel_old=1 (bare metal)
Replies: 1
Views: 616

RPi2 and kernel_old=1 (bare metal)

Hi, I'm porting some RYO operating systems to the RPi#. Everything seems okay with the RPi B/A/A+/0. And everything seems okay with the RPi2B.. as long as I include the HYP-to-SYS "preamble" to switch the processor mode before it actually jumps into my OS. (My OS uses (mostly) SYS and IRQ modes.) (A...
by k2tom
Sat Mar 26, 2016 1:44 pm
Forum: Bare metal, Assembly language
Topic: Firmware question?
Replies: 38
Views: 5091

Re: Firmware question?

dwelch67, No worries about "hijacking" the thread. I've learned a lot. This is truly one of those "I didn't know what I didn't know" moments. Going back a year, when I first got my RPi2B, I spent a few minutes looking at the bare metal threads at the time... changed the register base from 0x20000000...
by k2tom
Fri Mar 25, 2016 4:11 pm
Forum: Bare metal, Assembly language
Topic: RPi, RPi2 and RPi0 firmware compatibility?
Replies: 7
Views: 1717

Re: RPi, RPi2 and RPi0 firmware compatibility?

Thanks RST! My code (which starts at 0x8000) begins with a "stub" that jumps to my real code (at 0x9000). I changed the stub to - first thing - change the mode to SYS (or SVC). Of course that DIDN'T work. (That would've been TOO easy.) But at least I have a handle on WHY things are different. (And t...
by k2tom
Fri Mar 25, 2016 4:06 pm
Forum: Bare metal, Assembly language
Topic: Firmware question?
Replies: 38
Views: 5091

Re: Firmware question?

A related post set me on the right path (thanks RST!), namely that the newer firmware starts the 2B up in the HYP mode. So I'm trying (so far, unsuccessfully) to switch to SVC (or SYS) mode on startup.
by k2tom
Fri Mar 25, 2016 2:06 pm
Forum: Bare metal, Assembly language
Topic: Firmware question?
Replies: 38
Views: 5091

Firmware question?

Hi, My question is whether the Raspberry Pi firmware has changed (over the past year or so) SUCH THAT is assumes/requires some (newer?) structure of the kernel/kernel7.img file. I was always under the impression that - by default - the firmware loaded the IMG file to 0x8000 (in the ARM's address spa...
by k2tom
Mon Mar 21, 2016 6:35 pm
Forum: Bare metal, Assembly language
Topic: RPi, RPi2 and RPi0 firmware compatibility?
Replies: 7
Views: 1717

Re: RPi, RPi2 and RPi0 firmware compatibility?

I started with the 2016-03-18-raspian-jessie-lite.zip... opened the 2016-03-18-raspbian-jessie-lite.img... opened the 0.fat image... I copied all those files to the root directory of my uSD (including the overlays subdirectory)... I replaced kernel.img and kernel7.img with my "known working" home-gr...
by k2tom
Mon Mar 21, 2016 3:01 pm
Forum: Bare metal, Assembly language
Topic: RPi, RPi2 and RPi0 firmware compatibility?
Replies: 7
Views: 1717

Re: RPi, RPi2 and RPi0 firmware compatibility?

Thanks Dougie! I see things have changed a lot with the firmware structure since I first got my (RYO) "kernel7.img" running on the RPi2 (a little more than a year ago). So here's my status, which I'm hoping you (or anyone) can comment on (before I get my RPi3). (1) I copied the "0.fat" image (boot a...
by k2tom
Tue Mar 15, 2016 7:38 pm
Forum: Bare metal, Assembly language
Topic: RPi, RPi2 and RPi0 firmware compatibility?
Replies: 7
Views: 1717

RPi, RPi2 and RPi0 firmware compatibility?

Hi, I've been doing some bare metal projects on several of the RPi boards. (I have RPi A, A+, and B boards, and some RPi2B boards.) Everything seemed fine. I have copies of bootcode.bin and start.elf that are able to load and start my RPi and RPi2 kernels. And my config.txt file is a simple one-line...
by k2tom
Thu Feb 19, 2015 9:32 pm
Forum: Bare metal, Assembly language
Topic: Trying Bare Metal on Raspberry Pi 2
Replies: 98
Views: 34117

Re: Trying Bare Metal on Raspberry Pi 2

For what it's worth.. I just got my RPi2 ("6.28") Tuesday.. and finally got to play with it today (Thursday). Here's what I did: (I've been working on "bare metal" projects (mostly of the RYO OS flavor) on the RPi (A, A+ and B) for a while.) I copied bootcode.bin and start.elf from the raspbian down...

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