Adds registration and get/set functions for enabling/disabling the AArch64
execution state on AArch64 CPUs. By default AArch64 execution state is enabled
on AArch64 CPUs, setting the property to off, will disable the execution state.
The below QEMU invocation would have AArch64 execution state disabled.
$ ./qemu-system-aarch64 -machine virt -cpu cortex-a57,aarch64=off
Also adds stripping of features from CPU model string in acquiring the ARM CPU
by name.
Backports part of commit fb8d6c24b095c426151b9bba8c8b0e58b03d6503 from qemu
Prepare ARMCPRegInfo to support specifying two fieldoffsets per
register definition. This will allow us to keep one register
definition for banked registers (different offsets for secure/
non-secure world).
Also added secure state tracking field and flags. This allows for
identification of the register info secure state.
Backports commit c3e302606253a17568dc3ef30238f102468f7ee1 from qemu
