Review request: sparse CPU ID maps

[Adrian Chadd]

On 2 July 2016 at 17:08, Nathan Whitehorn <nwhitehorn at freebsd.org> wrote:
> A reasonable first pass at checking for this kind of bug is doing grep -lR
> '< mp_ncpus'. Running that on sys/arm and sys/arm64 shows the following
> files:
> arm/mv/armadaxp/armadaxp_mp.c
> arm/include/counter.h
> arm/broadcom/bcm2835/bcm2836.c
> arm/broadcom/bcm2835/bcm2836_mp.c
> arm/freescale/imx/imx6_mp.c
> arm/allwinner/aw_mp.c
> arm/rockchip/rk30xx_mp.c
> arm/amlogic/aml8726/aml8726_mp.c
> arm/samsung/exynos/exynos5_mp.c
> arm/arm/mp_machdep.c
> arm/nvidia/tegra124/tegra124_mp.c
> arm64/include/counter.h
> arm64/arm64/gic_v3.c
> arm64/arm64/gic_v3_its.c
> arm64/arm64/gicv3_its.c
>
> All of them should, in some sense, be CPU_FOREACH(), but it may not matter.
> For example, it may not be possible to have sparse CPU IDs on some or all of
> those SOCs. At least the generic ones (counter, mp_machdep.c, gic (why are
> there both gic_v3_its.c and gicv3_its.c?)) should be changed, I think.
> -Nathan

I think converting all the users over to the CPU_FOREACH thing is the
right way to go, even if the SOC doesn't require it. People do bring
up new systems by copy/pasta'ing an existing similar system, so we're
best served by having all the consumers migrated.

But, I'd do it in head/12. Early in head/12. :-P

-adrian