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

[Mark Millard]

On 2019-Apr-19, at 15:20, Mark Millard <marklmi at yahoo.com> wrote:

> 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.)


I forgot to mention, PowerISA 3.0B no longer lists information
about any of:

or 27,27,27
or 29,29,29
or 30,30,30

2.07 and 3.0B do list information for:

or 26,26,26

No prior ones do.


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