Re: [PATCH] ARM: tegra: add basic SecureOS support

[Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org>]

On 06/10/2013 03:14 AM, Russell King - ARM Linux wrote:
> On Mon, Jun 10, 2013 at 05:11:15PM +0900, Alexandre Courbot wrote:
>> On Sat, Jun 8, 2013 at 1:33 AM, Stephen Warren <swarren-3lzwWm7+Weoh9ZMKESR00Q@public.gmane.org> wrote:
>>>>> I think we need to separate the concept of support for *a* secure
>>>>> monitor, from support for a *particular* secure monitor.
>>>>
>>>> Agreed. In this case, can we assume that support for a specific secure
>>>> monitor is not arch-specific, and that this patch should be moved
>>>> outside of arch-tegra and down to arch/arm? In other words, the ABI of
>>>> a particular secure monitor should be the same no matter the chip,
>>>> shouldn't it?
>>>
>>> I would like to believe that the Trusted Foundations monitor had the
>>> same ABI irrespective of which Soc it was running on. However, I have
>>> absolutely no idea at all if that's true. Even if there's some common
>>> subset of the ABI that is identical across all SoCs, I wouldn't be too
>>> surprised if there were custom extensions for each different SoC, or
>>> just perhaps even each product.
>>>
>>> Can you research this and find out the answer?
>>
>> Will do. Information about TF is scarce unfortunately.
> 
> The answer is... there isn't a common ABI.  That is something I pressed
> ARM Ltd for when this stuff first appeared and they were adamant that
> they were not going to specify any kind of ABI for this interface.

Right, there certainly isn't a common ABI across all secure monitors,
but in this case I was wondering something more specific: whether for
this specific implementation/provider of a secure monitor, if they had a
consistent ABI across all SoCs (or even boards) that they implemented it on.