[WWWDocs] Deprecate support for non-thumb ARM devices

Richard Earnshaw (lists) Richard.Earnshaw@arm.com
Thu Feb 25 14:25:00 GMT 2016


On 25/02/16 14:15, David Brown wrote:
> On 25/02/16 14:32, Stefan Ring wrote:
>> On Thu, Feb 25, 2016 at 10:20 AM, Richard Earnshaw (lists)
>> <Richard.Earnshaw@arm.com> wrote:
>>> 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.
>>
>> Slightly off topic, but related: What does the "e" stand for? Also,
>> what does "l" stand for in armv5tel, which is what I usually get --
>> little endian?
> 
> <https://community.arm.com/groups/processors/blog/2011/11/02/arm-fundamentals-introduction-to-understanding-arm-processors>
> 
> <https://en.wikipedia.org/wiki/List_of_ARM_microarchitectures>
> 
> The "t" is thumb, 
Correct.

"e" means "DSP-like extensions",
Correct.  But there were other bits as well.

 and I suspect the "l"
> is a misprint for "j", meaning the Jazelle (Java) acceleration instructions.

No.  As I said earlier, it's nothing to do with the architecture, but
means the system is running little-endian.

R.



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