[PATCH v3] arch: arm64: add early_param idle=<wfi|yield|nop>

[Will Deacon]

On Tue, 04 Aug 2026 19:23:15 +0200, Yureka Lilian wrote:
> Overriding the idle mechanism might be useful for debugging and performance
> testing. Add a cmdline parameter for it, similar to the existing idle=
> parameter already present for the x86 and ppc architectures.
> 
> It is also useful on platforms where the WFI instruction misbehaves,
> such as Apple Silicon SoCs. Generally, a misbehaving instruction should
> be treated as an erratum and patched using the alternatives framework.
> However, in the Apple Silicon case we need more flexibility because it is
> difficult to detect whether the erratum applies. For example, Linux VMs
> inside macOS have the same MIDR and may even seem like they're running
> in EL2 in the case of NV, but should continue using WFI (it's trapped and
> handled correctly by the hypervisor there). Thus, we prefer to
> let the m1n1 bootloader add the idle=nop parameter[1].
> 
> [...]

Applied to arm64 (for-next/errata), thanks!

[1/1] arch: arm64: add early_param idle=<wfi|yield|nop>
      https://git.kernel.org/arm64/c/d97afae6f16a

Cheers,
-- 
Will

https://fixes.arm64.dev
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