64-bit RPi4B u-boot hangup with modern rpi firmware: some information (but investigative-toolbox limited)

[Mark Millard]

On 2020-Oct-13, at 23:18, Klaus Cucinauomo <maciphone2 at googlemail.com> wrote:

> Am 14.10.2020 um 07:52 schrieb Mark Millard <marklmi at yahoo.com>:
>> 
>> …...FreeBSD requires services from
>> armstub8-gic.bin that are not otherwise present as things
>> are (or that is my understanding).
> 
> as of today:  correct understanding
> 
>> 
>> ... I'll test vintages of start4*.elf and fixup4*.dat
>> pairs and see if that identifies a specific set of changes
>> to them...
> 
> IIRC „we" can hack armstubs but  we cannot hack  start4*.elf &  fixup4*.dat ,
> but you can take a hexdump of start4*.elf  to compare changes  if you feel like it,
> while I doubt that will easy find the cause(s)..

hexdump comparisons is not something I'm likely to do and is
not what I said I was going to do.

Types of changes are identified by the commit notes. It is
possible with what I'm doing that a firmware problem would
be identified that the rpi folks would work on. (Not
claiming to know it is likely or anything.)

I've already reported on the lists a patch for u-boot 2020.10
not avoiding stomping on memory owned by the armstub8-gic.bin
that FreeBSD uses. (It is not guaranteed to stomp on such
memory either: u-boot just does not reserve the memory area
that it should and so treats it as available for potential
use.)

If I had only focused on armstub8-gic.bin I never would have
found that problem. (Of course, if armstub8-gic.bin ends up
eliminated, the problem I found goes away too.)

Unfortunately, the patch does not fix the symptoms that
started this effort but the defect could lead to problems.

===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)