HiFive Unleashed support

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Summary

1. Pick a hart to boot on using hart lottery. This is an official RISC-V way to avoid booting on the management hart used in Linux. Management hart runs BBL initialization sequence and it releases main CPUs before it jumps to FreeBSD entry point itself. So it never wins the lottery.
2. Renumber CPUs early on boot so we can boot on any hart.

This fixes operation on HiFive Unleashed.

Test Plan

Tested in QEMU and HiFive Unleashed.

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Fix !SMP build.

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1. Store hart in struct pcpu
2. Store harts not CPUIDs in pmap->pm_active

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Use all_harts mask in release_aps()

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Fix bug: use CPU_FILL to fill up kernel pmap pm_active.
all_harts is not initialized yet in pmap_boostrap()

[markj]

sys/riscv/riscv/mp_machdep.c

398

Hmm. Looks like Linux assumes that hartIDs can fit in a cpuset. I guess we can assume that too, but IMO we should assert that hartids are < MAXCPU.

sys/riscv/riscv/pmap.c

4295

The var should be called "hart", ditto elsewhere.

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• Assert that hart < MAXCPU
• Rename cpu variable to hart