On Fri, Jan 09, 2015 at 10:16:32AM +0800, Wang, Yalin wrote: > > -----Original Message----- > > From: Russell King - ARM Linux [mailto:linux@xxxxxxxxxxxxxxxx] > > Sent: Friday, January 09, 2015 2:41 AM > > To: Wang, Yalin > > Cc: 'Will Deacon'; 'Ard Biesheuvel'; 'linux-kernel@xxxxxxxxxxxxxxx'; > > 'akinobu.mita@xxxxxxxxx'; 'linux-mm@xxxxxxxxx'; 'Joe Perches'; 'linux-arm- > > kernel@xxxxxxxxxxxxxxxxxxx' > > 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. -- FTTC broadband for 0.8mile line: currently at 9.5Mbps down 400kbps up according to speedtest.net. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>