[PATCH 0/1] armv8: reduce core errata dispatch work

[Ilias Apalodimas]

Thanks for the heads up Krzysztof

On Tue, May 26, 2026, 08:01 Krzysztof Kozlowski <krzk at kernel.org> wrote:

> On 24/05/2026 14:38, Josh Law wrote:
> > Hey folks,
> >
> > apply_core_errata() runs during early ARMv8 CPU entry, before
> > lowlevel_init(). Today it still checks the Cortex-A53 and Cortex-A57
> > paths even when the build has no matching core erratum enabled.
> >
> > This patch leaves that dispatch code out unless one of the supported
> > errata is enabled. For the A57 errata case, it reads MIDR_EL1 once and
> > reuses the extracted CPU part number.
> >
> > The erratum register writes stay behind the same CPU checks as before.
> > For qemu_arm64_defconfig, where none of these errata are enabled,
> > apply_core_errata() goes from 15 dispatch instructions to a single ret.
> > For ls2080aqds_qspi_defconfig, which keeps the A57 path, the dispatch
> > side goes from 33 instructions to 26. A KVM microbench of the same
> > dispatch sequences showed 1.30x for the no errata case and 1.09x for
> > the A57 miss case.
> >
> > Josh Law (1):
> >   armv8: reduce core errata dispatch work
>
> That's another identity from Josh Law, since all previous got NAKed, and
> 100% AI generated code without review and without tests (I don't believe
> what was claimed above).
>
> I recommend ignoring and here is some background:
>
>
> https://lore.kernel.org/all/cbd0aafa-bd45-4f4d-a2dd-440473657dba@lucifer.local/
>
> Best regards,
> Krzysztof
>