> -----Original Message----- > From: Russell King - ARM Linux [mailto:li...@arm.linux.org.uk] > Sent: Friday, January 09, 2015 7:11 PM > To: Wang, Yalin > Cc: 'Ard Biesheuvel'; 'Will Deacon'; 'linux-kernel@vger.kernel.org'; > 'akinobu.m...@gmail.com'; 'linux...@kvack.org'; 'Joe Perches'; > 'linux-arm- ker...@lists.infradead.org' > Subject: Re: [RFC V6 2/3] arm:add bitrev.h file to support rbit > instruction > > On Fri, Jan 09, 2015 at 10:16:32AM +0800, Wang, Yalin wrote: > > > -----Original Message----- > > > From: Russell King - ARM Linux [mailto:li...@arm.linux.org.uk] > > > Sent: Friday, January 09, 2015 2:41 AM > > > To: Wang, Yalin > > > Cc: 'Will Deacon'; 'Ard Biesheuvel'; > > > 'linux-kernel@vger.kernel.org'; 'akinobu.m...@gmail.com'; > > > 'linux...@kvack.org'; 'Joe Perches'; > > > 'linux-arm- ker...@lists.infradead.org' > > > Subject: Re: [RFC V6 2/3] arm:add bitrev.h file to support rbit > > > instruction > > > > > > The root cause is that the kernel being built is supposed to > > > support both > > > ARMv7 and ARMv6K CPUs. However, "rbit" is only available on > > > ARMv6T2 (thumb2) and ARMv7, and not plain ARMv6 or ARMv6K CPUs. > > > > > In the patch that you applied: > > 8205/1 add bitrev.h file to support rbit instruction > > > > I have add : > > + select HAVE_ARCH_BITREVERSE if ((CPU_V7M || CPU_V7) && !CPU_V6) > > > > If you build kernel support ARMv6K, should CONFIG_CPU_V6=y, isn't it ? > > Then will not build hardware rbit instruction, isn't it ? > > The config has: > > CONFIG_CPU_PJ4=y > # CONFIG_CPU_V6 is not set > CONFIG_CPU_V6K=y > CONFIG_CPU_V7=y > CONFIG_CPU_32v6=y > CONFIG_CPU_32v6K=y > CONFIG_CPU_32v7=y > > And no, the CONFIG_CPU_V* flags refer to the CPUs. The > CONFIG_CPU_32v* symbols refer to the CPU architectures. > 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? :) Thank you -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
