Re: [Qemu-devel] [PATCH v2 00/23] target-arm: add Security Extensions for CPUs

[Peter Maydell]

On 20 May 2014 16:43, Greg Bellows <address@hidden> wrote:
> My focus within Linaro is to add support for the security extension to qemu
> for ARMv7.  Given that we both started from Samsung's original patches our
> code is fairly similar.  However, it appears that your changes have also
> incorporated some ARMv8 64-bit changes, which at this point is out of my
> scope.

It shouldn't be out of scope in a general sense -- any design for
supporting the security extensions must at least consider how the
AArch64 security extensions would be supported, even if it does
not actually implement all the detail.

> I think we should wait for Peter to chime in on the approach as he had
> expressed interest in the more explicit registration approach that you have
> presented.  I threw my approach out there simply for consideration as I
> thought it addressed his goal for maintaining ARMv7 features as the
> "side-cases".

To clarify, what I meant by that is that I'd in general prefer to see
a design which implements AArch64 security as its primary thing
with the v7 security extension support as the "this is what differs"
part. (This is just a "seems like the obvious way to approach the
problem" guideline rather than a "must be this way" rule, though; I
haven't yet thought about the problem in sufficient depth.)

> Depending on what Peter and the qemu community believes is best, it sounds
> like we have two possible outcomes.
>
> Go entirely with your changes as they are similar to mine plus some
> additional changes for 64-bit.
> Go with my changes as a base incorporating some of your additions.

If we want to take the "put all the reginfo for a register in one place"
approach it sounds like it might be best to start with Fabian's patches
and incorporate specific fixes/improvements from your tree into
those as appropriate.

thanks
-- PMM