riscv: rework CPU identification [2/6]

[mhorne]

Summary

Call identify_cpu() earlier for the BSP.

It is advantageous to have knowledge of ISA features as early as
possible. For example, the presence of newer virtual memory extensions
may be useful to pmap_bootstrap().

To achieve this, split out the printf() parts of identify_cpu() into a
separate function, identify_cpu_report(). This latter function will be
called later in boot after the console has been initialized.

Plus, a small trick in init_secondary() allows us to avoid interlaced
output from concurrent calls to identify_cpu_report() as APs are
started.

[jhb]

sys/riscv/riscv/mp_machdep.c

291

On x86 this is called printcpuinfo(). arm64 appears to do this as a SYSINIT later in boot instead (cpu_features_sysinit).

I think I'd prefer to try to aim for some sort of consistency for function names maybe? x86 is a bit more of a mess as it splits identify_cpu up into multiple routines for multiple steps, but might be nice to call this printcpuinfo at least.

arm64 prints the info for the APs on the BSP FWIW in the sysinit rather than doing it during AP startup.

For x86 we assume all cores are the same and don't bother printing any features for APs.

[mhorne]

Rebase and rename to printcpuinfo().