On Thu, Mar 30, 2023 at 06:40:03PM -0700, Wing Li wrote: > Adding some clarifications. > > On Thu, Mar 30, 2023 at 6:13 AM Sudeep Holla <sudeep.holla@xxxxxxx> wrote: > > > On Thu, Mar 30, 2023 at 02:06:19PM +0200, Ulf Hansson wrote: > > > On Thu, 30 Mar 2023 at 11:34, Sudeep Holla <sudeep.holla@xxxxxxx> wrote: > > > > > > > > On Thu, Mar 30, 2023 at 02:12:49PM +0530, Maulik Shah wrote: > > > > > A switch from OSI to PC mode is only possible if all CPUs other than > > the > > > > > calling one are OFF, either through a call to CPU_OFF or not yet > > booted. > > > > > > > > > > > > > As per the spec, all cores are in one of the following states: > > > > - Running > > > > - OFF, either through a call to CPU_OFF or not yet booted > > > > - Suspended, through a call to CPU_DEFAULT_SUSPEND > > > > > > > > Better to provide full information. > > > > The spec quoted above only applies when switching from platform-coordinated > mode to OS-initiated mode. > > For switching from OS-initiated to platform-coordinated, which is the case > Maulik is referring to, section 5.20.2 of the spec specifies: > "A switch from OS-initiated mode to platform-coordinated mode is only > possible if all cores other than the calling one are OFF, either through a > call to CPU_OFF or not yet booted." > > My bad, I read/imagined it as PC->OSI mode couple of times even though it is pretty explicit. Sorry for that. And thanks a lot for pointing that out. -- Regards, Sudeep
