[WWWDocs] Deprecate support for non-thumb ARM devices

Richard Earnshaw (lists) Richard.Earnshaw@arm.com
Thu Feb 25 09:20:00 GMT 2016

On 24/02/16 17:38, Joseph Myers wrote:
> On Wed, 24 Feb 2016, Richard Earnshaw (lists) wrote:
>> After discussion with the ARM port maintainers we have decided that now
>> is probably the right time to deprecate support for versions of the ARM
>> Architecture prior to ARMv4t.  This will allow us to clean up some of
> Should this include -march=armv5 and -march=armv5e (the theoretical 
> no-Thumb versions of v5, which may never have had any corresponding 
> processors)?

It's a fair question, but the answer is no, this isn't necessary.

The point is to permit the compiler to use interworking compatible
sequences of code when generating ARM code, not to force users to use
Thumb code.  The necessary instruction (BX) is available in armv5 and
armv5e, even though Thumb is not supported in those architecture variants.

It might be worth deprecating v5 and v5e at some point in the future: to
the best of my knowledge no v5 class device without Thumb has ever
existed - but it's not a decision that needs to be related to this proposal.


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