Re: [PATCH 10/18] arm64: Support hugetlb vmemmap optimization

[Catalin Marinas]

On Wed, Jul 08, 2026 at 03:11:20AM +0000, James Houghton wrote:
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index b3afe0688919..cf4bd6bd7f11 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -259,6 +259,7 @@ config ARM64
>  	select USER_STACKTRACE_SUPPORT
>  	select VDSO_GETRANDOM
>  	select VMAP_STACK
> +	select ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP if ARM64_WANT_OPTIMIZE_HUGETLB_VMEMMAP

Nit: we try to keep this list alphabetically ordered.

>  	help
>  	  ARM 64-bit (AArch64) Linux support.
>  
> @@ -1607,6 +1608,17 @@ config ARCH_SPARSEMEM_ENABLE
>  	def_bool y
>  	select SPARSEMEM_VMEMMAP_ENABLE
>  
> +config ARM64_WANT_OPTIMIZE_HUGETLB_VMEMMAP
> +	bool "Enable support for HugeTLB Vmemmap Optimization (HVO)"
> +	default n

Nit: 'n' is the default already.

> +	depends on HUGETLB_PAGE && SPARSEMEM_VMEMMAP && ARM64_HW_AFDBM
> +	help
> +	  Enable support for HVO. When enabled, late-onlining of CPUs that do

I'd drop 'of', not sure how it reads better. Maybe just 'late CPUs ...
will not be onlined'.

> +	  not support features required by HVO will not be onlined if all boot
> +	  CPUs do have such support.
> +
> +	  If unsure, say N
> +
>  config HW_PERF_EVENTS
>  	def_bool y
>  	depends on ARM_PMU

-- 
Catalin