@Gigamaxx
XCPM bootstrap has been changed and patch need to update, by studying AMD patches Mask, find that using Mask as search / replace pattern for XCPM bootstrap is rather simply.
Original 10.13 XCPM bootstrap decoded by PMHeart, byte 1,2,3,6 change periodically while byte 4,5,7,8 never change from 10.13 to 11.3, byte 4,5,6,7,8, should be used as search pattern.
Set find Mask as FFFF00FFFF, where 00 are unknown / any, FF search pattern
Since only need change byte C4 to C6 and find Mask already function as filter, then set replace Mack to FF00000000 as replace pattern should be enough, where FF values should be replaced, 00 remain unchanged
Tested work with Haswell Celeron G1840 / SKL Pentium G4400 + OC 0.6.6, at least work from Mojave10.14.6 to Big Sur 11.3.