Only covers EAX for now.
const Xcr0 = packed struct(u32)
const Xcr0 = packed struct(u32) {
x87: bool,
sse: bool,
avx: bool,
bndreg: bool,
bndcsr: bool,
opmask: bool,
zmm_hi256: bool,
hi16_zmm: bool,
pt: bool,
pkru: bool,
pasid: bool,
cet_u: bool,
cet_s: bool,
hdc: bool,
uintr: bool,
lbr: bool,
hwp: bool,
xtilecfg: bool,
xtiledata: bool,
apx: bool,
_reserved: u12,
}