ARC: Boot_time test not functioning

[nashif]

Reported by Chuck Jordan:

The following tests malfunction for ARC cpu targets:

tests/benchmarks/boot_time legacy/benchmark/boot_time/<microkernel,nanokernel>

When CONFIG_BOOT_TIME_MEASUREMENT is defined, some very early initialization is supposed to assign the value __start_tsc. This can't be done with ARC because _tsc_read is implemented to rely on tick interrupts, and that hasn't come alive during this early time.

What could be done, is the ARC timer0 could be activated very early, w/o it causing an interrupt, just so that COUNT register increments. __start_tsc could be initialized to zero early (but after bss zeroed if this is in bss). Or perhaps just let the bss zeroing zero it.

Then later, when the timer0 is to be activated for interrupts, to the necessary math to keep the COUNT up to that point as part of the TIME being maintained by the sys_clock.c implementation. In this way, 64-bit time, as returned by _tsc_read(), can be functional from very early init.

(Imported from Jira ZEP-1747)

[nashif]

by Mark Linkmeyer:

Ruud Derwig , can you please assess this bug and set an appropriate priority? Thx.

[nashif]

by Chuck Jordan:

priority is low