Re: [RFC PATCH v2] arm64: barrier: add macro dgh() to control memory accesses merging
From: Catalin Marinas <catalin.marinas@arm.com>
Date: 2021-10-15 18:00:05
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On Fri, Oct 15, 2021 at 05:05:11PM +0800, Xiongfeng Wang wrote:
quoted hunk ↗ jump to hunk
diff --git a/arch/arm64/include/asm/barrier.h b/arch/arm64/include/asm/barrier.h index 451e11e5fd23..d71a7457d619 100644 --- a/arch/arm64/include/asm/barrier.h +++ b/arch/arm64/include/asm/barrier.h@@ -18,6 +18,14 @@ #define wfe() asm volatile("wfe" : : : "memory") #define wfi() asm volatile("wfi" : : : "memory") +/* + * Data Gathering Hint: + * This instruction prohibits merging memory accesses with Normal-NC or + * Device-GRE attributes before the hint instruction with any memory accesses + * appearing after the hint instruction. + */ +#define dgh() asm volatile("hint #6" : : : "memory")
On its own, this patch doesn't do anything. It's more interesting to see how it will be used and maybe come up with a common name that other architectures would share (or just implement as no-opp). I'm not sure there was any conclusion last time we discussed this. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel