[RFC V6 2/3] arm:add bitrev.h file to support rbit instruction
From: Russell King - ARM Linux <hidden>
Date: 2014-11-13 23:53:36
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On Fri, Oct 31, 2014 at 01:42:44PM +0800, Wang, Yalin wrote:
quoted hunk
This patch add bitrev.h file to support rbit instruction, so that we can do bitrev operation by hardware. Signed-off-by: Yalin Wang <redacted> --- arch/arm/Kconfig | 1 + arch/arm/include/asm/bitrev.h | 21 +++++++++++++++++++++ 2 files changed, 22 insertions(+) create mode 100644 arch/arm/include/asm/bitrev.hdiff --git a/arch/arm/Kconfig b/arch/arm/Kconfig index 89c4b5c..be92b3b 100644 --- a/arch/arm/Kconfig +++ b/arch/arm/Kconfig@@ -28,6 +28,7 @@ config ARM select HANDLE_DOMAIN_IRQ select HARDIRQS_SW_RESEND select HAVE_ARCH_AUDITSYSCALL if (AEABI && !OABI_COMPAT) + select HAVE_ARCH_BITREVERSE if (CPU_V7M || CPU_V7)
Looking at this, this is just wrong. Take a moment to consider what happens if we build a kernel which supports both ARMv6 _and_ ARMv7 CPUs. What happens if an ARMv6 CPU tries to execute an rbit instruction? Second point (which isn't obvious from your submissions on-list) is that you've loaded the patch system up with patches for other parts of the kernel tree for which I am not responsible for. As such, I can't take those patches without the sub-tree maintainer acking them. Also, the commit text in those patches look weird: 6fire: Convert byte_rev_table uses to bitrev8 Use the inline function instead of directly indexing the array. This allows some architectures with hardware instructions for bit reversals to eliminate the array. Signed-off-by: Joe Perches <(address hidden)> Signed-off-by: Yalin Wang <(address hidden)> Why is Joe signing off on these patches? As his is the first sign-off, one assumes that he was responsible for creating the patch in the first place, but there is no From: line marking him as the author. Shouldn't his entry be an Acked-by: ? Confused. -- FTTC broadband for 0.8mile line: currently at 9.5Mbps down 400kbps up according to speedtest.net.