In message 43D9E2AB.5020108@sbcglobal.net you wrote:
- U-boot Scripting occurs which copies Linux OS from flash into where?
Next highest or lowest portion of RAM? Is it dependent on whether
On PowerPC the kernel starts always at physical address 0x0000 in RAM ==> lowest address.
dual-stage vmlinux.initrd or single-stage vmlinux is used or not?
With U-Boot you use neither vmlinux.initrd nor vmlinux but uImage, eventually with a separate ramdisk image, or eventually a combined "multi-file image".
At power-up, with U-Boot 1.1.4 being unusually low-RAM-based before starting up (instead of executing straight out of ROM), I noticed that despite being relocated to MONITOR (higher RAM) region, the PIT exception vector appears to be active in 0000_10c0-ish.
U-Boot installs it's own exception vectors.
Despite this RAM-to-RAM relocation, this "mtest" clobbering of the 0000_10C0 region caused Machine Exception error whenever I attempt to
Yes, of course. What else do you expect when you overwrite active code?
perform memory test over this supposedly former exception vector region.
Former and current in your case.
I thought that the objective during U-boot relocation was to ensure a completely discontinued RAM region (formerly occupied by U-boot ROM-based session).
I cannot parse this. Pleasee see the README for the U-Boot memory layout. It's all written there. Just RTFM.
- Where do I go from there with regard to the 0000_1000
(PIT_EXCEPTION). Isn't the PIT specific to Motorola 8xx-series (this here is a PPC 405). What exception did the lib_ppc/start.S/trap_init() exactly skipped? Skipped an exception mentioned vaguely in this source code vaguely. Do I need to tweak the trap_init() some more to relocate these untransfered exception vectors into the high MONITOR region?
I really don't understand the question, nor your concerns. The code is working find on many, many boards. No tweaking isnecessary.
- And lastly, do I go high or low for Linux OS?
I tend to keep my feet on the ground; no idea what you do.
What exactly is the question? "go high"??? Can't parse that.
Best regards,
Wolfgang Denk