Android and compatibility with deprecated armv7 instructions

[Måns Rullgård]

Will Deacon <will.deacon at arm.com> writes:

> On Thu, Jul 03, 2014 at 06:05:58PM +0100, Russell King - ARM Linux wrote:
>> On Thu, Jul 03, 2014 at 05:22:30PM +0100, Grant Likely wrote:
>> > So, no. I completely reject any notion that breaking existing apps is
>> > okay. If we're going to say that v8 still supports 32-bit apps, then
>> > it has to be all of v7, not just the 'good' bits. Nor do I think
>> > saying "it's just a bunch of games" justifies anything. We're kernel
>> > engineers. Applications are applications and we don't break userspace.
>> > Period.
>> 
>> +1 on all points above.  I'd go further - if we're going to say that v8
>> still supports 32-bit apps, that covers at least v6 *as well*.
>
> We've never pretended to support anything other than ARMv8 in the compat
> layer. uname even reports this in the machine name.
>
> If people are suddenly so concerned about *full* compatibility with an ARMv7
> kernel, that needs a lot more than just SWP emulation:
>
>   - Alignment fixups for ldm/stm

No ARM variant ever supported unaligned ldm/stm.

-- 
Måns Rullgård
mans at mansr.com