On Mon, Dec 13, 2021 at 03:26:58PM +0100, Pierre Morel wrote: > > Why is this assumption necessary? The statement that Linux runs only > > with horizontal polarization is not true. > > > > Right, I will rephrase this as: > > "Polarization change is not taken into account, QEMU intercepts queries for > polarization change (PTF) and only provides horizontal polarization > indication to Guest's Linux." > > @Heiko, I did not find any usage of the polarization in the kernel other > than an indication in the sysfs. Is there currently other use of the > polarization that I did not see? You can change polarization by writing to /sys/devices/system/cpu/dispatching. Or alternativel use the chcpu tool to change polarization. There is however no real support for vertical polarization implemented in the kernel. Therefore changing to vertical polarization is _not_ recommended, since it will most likely have negative performance impacts on your Linux system. However the interface is still there for experimental purposes.
