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Re: [PATCH] MIPS: Kconfig: microMIPS and SmartMIPS are mutually exclusiv

To: "Maciej W. Rozycki" <macro@linux-mips.org>
Subject: Re: [PATCH] MIPS: Kconfig: microMIPS and SmartMIPS are mutually exclusive
From: Ralf Baechle <ralf@linux-mips.org>
Date: Tue, 3 Jun 2014 14:24:51 +0200
Cc: Markos Chandras <markos.chandras@imgtec.com>, linux-mips@linux-mips.org
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On Tue, Jun 03, 2014 at 12:18:43PM +0100, Maciej W. Rozycki wrote:

>  Do we need this CPU_HAS_SMARTMIPS setting at all?  Can't we just 
> save/restore this SmartMIPS ACX register on context switches where 
> available (straightforward to detect at the run time) and have the 
> relevant pieces of code excluded (#ifdef-ed out or suchlike) on 
> non-supported configurations such as microMIPS or MIPS64?

SmartMIPS has new instructions which are hardcoded in various assembler
fragments, where something like if (cpu_has_smartmips) won't work.
So until a more complex solution is implemented CPU_HAS_SMARTMIPS is
what there is.

  Ralf

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