head -r346144 vs. "or 27,27,27" use (via cpu_spinwait)

[Mark Millard]

There still seems to be:

/usr/src/sys/powerpc/include/cpu.h:#define      cpu_spinwait()          __asm __volatile("or 27,27,27") /* yield */

used in powerpc_ipi_handler and ofw_rendezvous_dispatch
and mpc85xx_jog_set_int .

(It is not clear to me what the status of "or 27,27,27" is
on older processors, like in PowerMacs. 27 was not
documented before PowerISA 2.06 . (I looked in  2.03, 2.04,
2.05, 2.06B V2, 2.07, and 3.0B.)


===
Mark Millard
marklmi at yahoo.com
( dsl-only.net went
away in early 2018-Mar)