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Re: [WWWDocs] Deprecate support for non-thumb ARM devices
- From: "Richard Earnshaw (lists)" <Richard dot Earnshaw at arm dot com>
- To: Joseph Myers <joseph at codesourcery dot com>
- Cc: gcc-patches <gcc-patches at gcc dot gnu dot org>, gcc at gcc dot gnu dot org, Ramana Radhakrishnan <Ramana dot Radhakrishnan at arm dot com>, Kyrylo Tkachov <Kyrylo dot Tkachov at arm dot com>, "nickc at redhat dot com" <nickc at redhat dot com>
- Date: Thu, 25 Feb 2016 09:20:33 +0000
- Subject: Re: [WWWDocs] Deprecate support for non-thumb ARM devices
- Authentication-results: sourceware.org; auth=none
- References: <56CDB728 dot 1050300 at arm dot com> <alpine dot DEB dot 2 dot 10 dot 1602241734510 dot 27089 at digraph dot polyomino dot org dot uk>
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
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.