Re: RFD: Does CONFIG_X86_LOCAL_APIC still make sense?

From: Ingo Molnar
Date: Fri Oct 11 2013 - 02:20:13 EST



* H. Peter Anvin <hpa@xxxxxxxxx> wrote:

> I'm trying to wrap my head around if there are use cases where disabling
> either CONFIG_X86_UP_APIC or CONFIG_X86_LOCAL_APIC would ever make sense
> anymore.
>
> I am guessing there are probably some small number of embedded systems
> which still don't have LAPICs, but is it a significant number and does
> anyone care for new kernels? We are not talking about discontinuing
> support for non-APIC configurations, just the configuration option.

I guess it depends on the kernel size difference. If it's more than just a
few K then a patch will creep back via some CONFIG_EXPERT "reduce kernel
bloat" route.

The thing is, if we allow non-apic configurations then we have paid most
of the modularization, #ifdef and general maintenance price already.
Adding a Kconfig just makes it more testable and breakages more apparent.

Unless I missed some aspects of this that would allow us to simplify code
significantly that is.

Thanks,

Ingo
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