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Re: [WWWDocs] Deprecate support for non-thumb ARM devices
- From: David Brown <david at westcontrol dot com>
- To: Stefan Ring <stefanrin at gmail dot com>, "Richard Earnshaw (lists)" <Richard dot Earnshaw at arm dot com>
- Cc: Joseph Myers <joseph at codesourcery dot com>, 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 15:15:55 +0100
- 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> <56CEC761 dot 3060204 at arm dot com> <CAAxjCEyoF+bs2njh_oi7oNHkkddN9AVSPecgQVsKygbeNmrBPw at mail dot gmail dot com>
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?
The "t" is thumb, "e" means "DSP-like extensions", and I suspect the "l"
is a misprint for "j", meaning the Jazelle (Java) acceleration instructions.
> I have no idea if there is an authoritative source for these host
> specifications and cannot find any. config.guess seems to just rely on
> uname -m.