Re: [PATCH v6 2/9] arm64: report address tag when FEAT_MTE_TAGGED_FAR is supported

[Mark Brown]

On Wed, Jun 11, 2025 at 10:41:00AM +0100, Yeoreum Yun wrote:

> +HWCAP3_MTE_FAR
> +    Functionality implied by ID_AA64PFR2_EL1.MTEFAR == 0b0001.

> +Applications should interpret the values of these bits based on
> +the support for the 'mte_far' hwcap. If the support is not present,
> +the values of these bits should be considered as undefined otherwise valid.

The constant is HWCAP3_MTE_FAR and the cpuinfo is mtefar:

> +	[KERNEL_HWCAP_MTE_FAR]		= "mtefar",

The reference to the hwcap should probably be one of these, I'd go for
HWCAP3_MTE_FAR since it says hwcap.

>  	/*
>  	 * The architecture specifies that bits 63:60 of FAR_EL1 are UNKNOWN
>  	 * for tag check faults. Set them to corresponding bits in the untagged
> -	 * address.
> +	 * address if ARM64_MTE_FAR isn't supported.
> +	 * Otherwise, bits 63:60 of FAR_EL1 are KNOWN.

Should this say UNKNOWN?

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