Re: [PATCH] hw/acpi: refactor acpi hp modules so that targets can just use what they need

[Ani Sinha]

On Thu, 12 Aug 2021, Ani Sinha wrote:

> Currently various acpi hotplug modules like cpu hotplug, memory hotplug, pci
> hotplug, nvdimm hotplug are all pulled in when CONFIG_ACPI_X86 is turned on.
> This brings in support for whole lot of subsystems that some targets like
> mips does not need. They are added just to satisfy symbol dependencies. This
> is ugly and should be avoided. Targets should be able to pull in just what 
> they
> need and no more. For example, mips only needs support for PIIX4 and does not
> need acpi pci hotplug support or cpu hotplug support or memory hotplug support
> etc. This change is an effort to clean this up.
> In this change, new config variables are added for various acpi hotplug
> subsystems. Targets like mips can only enable PIIX4 support and not the rest
> of all the other modules which were being previously pulled in as a part of
> CONFIG_ACPI_X86. Function stubs make sure that symbols which piix4 needs but
> are not required by mips (for example, symbols specific to pci hotplug etc)
> are available to satisfy the dependencies.
>
> Currently, this change only addresses issues with mips malta targets. In 
> future
> we might be able to clean up other targets which are similarly pulling in lot
> of unnecessary hotplug modules by enabling ACPI_X86.
>
> This change should also address issues such as the following:
> https://gitlab.com/qemu-project/qemu/-/issues/221
> https://gitlab.com/qemu-project/qemu/-/issues/193

I do not have a cross compiled mips64 vmlinux handy, so can't verify that
issue #193 was indeed resolved. I have verified that #221 was indeed
fixed.