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RNDRRS, Reseeded Random Number

The RNDRRS characteristics are:

Purpose

Reseeded Random Number. Returns a 64-bit random number which is reseeded from the True Random Number source at an IMPLEMENTATION DEFINED rate.

If the hardware returns a genuine random number, PSTATE.NZCV is set to 0b0000.

If the instruction cannot return a genuine random number in a reasonable period of time, PSTATE.NZCV is set to 0b0100 and the data value returned in UNKNOWN.

RNDRRS is a read-only register.

Configuration

This register is present only when ARMv8.5-RNG is implemented. Otherwise, direct accesses to RNDRRS are UNDEFINED.

RW fields in this register reset to architecturally UNKNOWN values.

Attributes

RNDRRS is a 64-bit register.

Field descriptions

The RNDRRS bit assignments are:

6362616059585756555453525150494847464544434241403938373635343332
RNDRRS
RNDRRS
313029282726252423222120191817161514131211109876543210

RNDRRS, bits [63:0]

Reseeded Random Number. Returns a 64-bit Random Number which is reseeded from the True Random Number source immediately before this read.

This field resets to an architecturally UNKNOWN value.

Accessing the RNDRRS

Accesses to this register use the following encodings:

MRS <Xt>, RNDRRS

op0op1CRnCRmop2
0b110b0110b00100b01000b001
if PSTATE.EL == EL0 then
    return RNDRRS;
elsif PSTATE.EL == EL1 then
    return RNDRRS;
elsif PSTATE.EL == EL2 then
    return RNDRRS;
elsif PSTATE.EL == EL3 then
    return RNDRRS;
              


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