[Question] vendor-specific cpu enable-method

Masahiro Yamada yamada.masahiro at socionext.com
Wed Sep 12 18:23:35 PDT 2018


Sorry if I am asking a stupid question.

For arm64, there are only 2 cpu methods, psci and spin-table.

Why do we still allow vendor-specific methods upstreamed
for arm 32bit ports?

To me, it looks like SoC vendors continue inventing
different (but similar) ways to do the same thing.

It is a historical reason for old platforms.

However, if I look at Documentation/devicetree/bindings/arm/cpus.txt
enable-method properties are still increasing.

psci is available in arch/arm/kernel/psci_smp.c,
but not all SoCs support the security extension.
Is there a simpler one like spin-table available for arm32?

If we force generic methods like psci or spin-table
for new platforms, we can stop proliferated smp code.
(Of course, we are just shifting the complexity
from the kernel to firmware.)

Am I missing something?

Best Regards
Masahiro Yamada

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