RE: [RFC V6 2/3] arm:add bitrev.h file to support rbit instruction

["Wang, Yalin" <Yalin.Wang@sonymobile.com>]

> -----Original Message-----
> From: Russell King - ARM Linux [mailto:linux@arm.linux.org.uk]
> Sent: Thursday, January 15, 2015 12:38 AM
> To: Wang, Yalin
> Cc: 'Ard Biesheuvel'; 'Will Deacon'; 'linux-kernel@vger.kernel.org';
> 'akinobu.mita@gmail.com'; 'linux-mm@kvack.org'; 'Joe Perches'; 'linux-arm-
> kernel@lists.infradead.org'
> Subject: Re: [RFC V6 2/3] arm:add bitrev.h file to support rbit instruction
> 
> On Fri, Jan 09, 2015 at 08:40:56PM +0800, Wang, Yalin wrote:
> > Oh, I see,
> > How about change like this:
> > +	select HAVE_ARCH_BITREVERSE if ((CPU_V7M || CPU_V7) && !CPU_V6 &&
> > +!CPU_V6K)
> > I am not sure if I also need add some older CPU types like !CPU_ARM9TDMI
> &&　!CPU_ARM940T ?
> >
> > Another solution is:
> > +	select HAVE_ARCH_BITREVERSE if ((CPU_32V7M || CPU_32V7) && !CPU_32V6
> > +&& !CPU_32V5 && !CPU_32V4 && !CPU_32V4T && !CPU_32V3)
> >
> > By the way, I am not clear about the difference between CPU_V6 and
> > CPU_V6K, could you tell me? :)
> 
> I think
> 
> 	select HAVE_ARCH_BITREVERSE if (CPU_32v7M || CPU_32v7) && !CPU_32v6
> 
> is sufficient - we don't support mixing pre-v6 and v6+ CPU architectures
> into a single kernel.
> 
Ok, I will re-send a patch. 

Thanks