Platform configuration (was: Re: CONFIG_PPC != Mac)

[Benjamin Herrenschmidt]

>First, kernel compile times are only fairly large after a big update, when
>I do `make dep clean zImage'. Second, the proportion of time spend in the
>specific PPC code (mostly arch/ppc and drivers/macintosh) is rather small.
>Third, building a minimal kernel image for each machine would involve a
>ton (and that's an undrestatement) of kernel options: CONFIG_INTC_8259,
>CONFIG_INTC_POWERMAC, CONFIG_INTC_OPENPIC and others for the interrupt
>controllers, half a dozen or so CONFIG_RTC types, same for CONFIG_NVRAM
>and a few other things I surely forget. The only reasonable solution is to
>aim for the smallest runtime kernel image.

Well, an easy first step is to have those per-machine cumulative compile
options so you can choose pmac only, pmac+chrp, etc...

That's only a few more config stuffs (CONFIG_PPC_PMAC, CONFIG_PPC_PREP,
etc...), the core code wouldn't need to change. We can even optimize the
various if (_machine == xxxx) using maros that get resolved to a constant
when only one machine type is compiled in.

Ben.


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