Re: [PATCH] arch-armv7a.inc: default to Thumb2 instruction set for armv7a and above

[Andre McCurdy <armccurdy@gmail.com>]

On Sat, May 19, 2018 at 12:41 AM, Martin Jansa <martin.jansa@gmail.com> wrote:
> On Sat, May 19, 2018 at 12:31:51AM -0700, Andre McCurdy wrote:
>> On Sat, May 19, 2018 at 12:11 AM, Martin Jansa <martin.jansa@gmail.com> wrote:
>> > On Fri, May 18, 2018 at 11:48:45PM -0700, Andre McCurdy wrote:
>> >> On Fri, May 18, 2018 at 10:42 PM, Martin Jansa <martin.jansa@gmail.com> wrote:
>> >> > This variable was always meant to be used from DISTRO config
>> >>
>> >> I'm not sure if that's true. Do you have a reference?
>> >
>> > http://git.openembedded.org/openembedded-core/commit/?id=951200673af27538beaef647a33308b4f15d1fb0
>> > "in case we have MACHINE without "thumb" in TUNE_FEATURES and distro setting ARM_INSTRUCTION_SET to "thumb""
>> >
>> > https://github.com/Angstrom-distribution/meta-angstrom/blob/master/conf/distro/include/angstrom.inc#L39
>> > https://github.com/shr-distribution/meta-smartphone/blob/fido/meta-shr-distro/conf/distro/shr.conf#L150
>>
>> Certainly there are distros which force ARM_INSTRUCTION_SET. I'm not
>> sure if that's evidence that machines shouldn't set a default though?
>
> It's still more evidence then what you've shown that it should be in
> machine config.

I had two criteria for this change:

  1) Only change the default for cores which support Thumb2.

  2) Don't have any effect on distros or recipes which already define
their own policy for setting ARM_INSTRUCTION_SET (ie don't use
over-rides).

Setting a weak default from armv7a.inc seems to be the simplest and
cleanest way to meet those two criteria.