purpose of RSDIS in ACTLR ?

There are discrepancies between the two documents but in this case it is not an error. When RSDIS is set, the return address stack pointer behaves differently in Cortex-R4 and Cortex-R5. If you will notice, when the prediction is forced to a fixed direction (through the BP field in the ACTLR),  the global history table also behaves differently.

There are discrepancies between the two documents but in this case it is not an error. When RSDIS is set, the return address stack pointer behaves differently in Cortex-R4 and Cortex-R5. If you will notice, when the prediction is forced to a fixed direction (through the BP field in the ACTLR),  the global history table also behaves differently.