Messages in this thread | | | Date | Fri, 15 Oct 2021 18:59:58 +0100 | From | Catalin Marinas <> | Subject | Re: [RFC PATCH v2] arm64: barrier: add macro dgh() to control memory accesses merging |
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On Fri, Oct 15, 2021 at 05:05:11PM +0800, Xiongfeng Wang wrote: > 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
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