[U-Boot] ARM: interrupt_init before relocation, write fails

[Albert ARIBAUD <albert.u.boot@aribaud.net>]

Hi Joe,

On Wed, 6 Nov 2013 09:18:53 -0700, Joe Kulikauskas
<jkulikauskas@cardinalpeak.com> wrote:

> Hi,
> 
> Rob, yes that's correct.
> 
> To Albert's question: the disassembled instruction I had showed
> LDR       R3,ff0a0fc0 is load of r3 with address of the variable holding
> the stack address;  "this write" is the str which I've now copied in below.
> IRQ_STACK_START_IN = gd->irq_sp + 8;
> ff0a0fb0: e5992044 ldr r2, [r9, #68] ; 0x44
> ff0a0fb4: e2822008 add r2, r2, #8
> ff0a0fb8: e5832000 str r2, [r3]
> 
> For my target, IIRC the write to flash caused problem in the flash
> controller hardware, breaking further instruction fetches.  On other
> platforms the write to flash may fail silently.  But the issue is that
> interrupt_init() moving into board_init_f (i.e. before relocation)
> generally just doesn't work right.
> 
> Joe

Thanks Rob and Joe for the clarification.

Indeed interrupt_init() cannot execute before relocation as it sets
globals.

Further, interrupt_init() uses globals to communicate with start.S.
This should be changed. I understand that is because the interrupt
handlers actually set the interrupt stack when they are invoked -- and
that is unnecessary; stacks should be set up as soon as their addresses
are known.

I'll revert the patch as soon as I finish getting the current PRs in.

I have a start.S rewrite effort underway whcuh I should post soon.
I'll add to it a change to the way stacks are initialized.

Amicalement,
-- 
Albert.