via cpuctl(4) driver. Two new CPUCTL_MSRSBIT and CPUCTL_MSRCBIT ioctl(2)
calls treat the data field of the argument struct passed as a mask
and set/clear bits of the MSR register according to the mask value.
- Allow user to perform atomic bitwise AND and OR operaions on MSR registers
via cpucontrol(8) utility. Two new operations ("&=" and "|=") have been
added. The first one applies bitwise AND operaion between the current
contents of the MSR register and the mask, and the second performs bitwise
OR. The argument can be optionally prefixed with "~" inversion operator.
This allows one to mimic the "clear bit" behavior by using the command
like this:
cpucontrol -m 0x10&=~0x02 # clear the second bit of TSC MSR
Inversion operator support in all modes (assignment, OR, AND).
Approved by: re (kib)
MFC after: 1 month
9a7ae64d55