From mboxrd@z Thu Jan  1 00:00:00 1970
From: Scott Wood <scottwood@freescale.com>
Date: Thu, 15 Mar 2012 16:25:41 -0500
Subject: [U-Boot] [PATCH v4 14/27] Introduce generic pre-relocation
	board_f.c
In-Reply-To: <CAPnjgZ1ngBc4SdJbiemQu2znprZ6iwjVRotGMcdVKhdgDSr7tQ@mail.gmail.com>
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	<CAPnjgZ1ngBc4SdJbiemQu2znprZ6iwjVRotGMcdVKhdgDSr7tQ@mail.gmail.com>
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On 03/15/2012 04:23 PM, Simon Glass wrote:
>>> +static int reserve_stacks(void)
>>> +{
>>> +     /* setup stack pointer for exceptions */
>>> +     gd->irq_sp = gd->dest_addr_sp;
>>> +#ifdef CONFIG_USE_IRQ
>>> +     gd->dest_addr_sp -= (CONFIG_STACKSIZE_IRQ + CONFIG_STACKSIZE_FIQ);
>>> +     debug("Reserving %zu Bytes for IRQ stack at: %08lx\n",
>>> +             CONFIG_STACKSIZE_IRQ + CONFIG_STACKSIZE_FIQ, gd->dest_addr_sp);
>>> +
>>> +     /* 8-byte alignment for ARM ABI compliance */
>>> +     gd->dest_addr_sp &= ~0x07;
>>> +#endif
>>> +     /* leave 3 words for abort-stack, plus 1 for alignment */
>>> +     gd->dest_addr_sp -= 16;
>>> +
>>> +     return 0;
>>> +}
>>
>> What does "leave 3 words for abort-stack, plus 1 for alignment" mean in
>> a generic context?  Certainly we shouldn't have references to things
>> like FIQ or ARM ABI.
> 
> This is limited to code which has CONFIG_USE_IRQ in it. Maybe this
> function will have to be per-architecture?

If CONFIG_USE_IRQ is ARM-specific, perhaps it needs a better name.

>> Do all architectures U-Boot supports have a stack that grows downward?
> 
> So far I have included ARM, x86 and PowerPC. If we add other archs to
> generic board init, we will need to look at this.

So it's not so much "generic" as supports more than one architecture.

-Scott