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OSDTRTX_EL1, OS Lock Data Transfer Register, Transmit

The OSDTRTX_EL1 characteristics are:

Purpose

Used for save/restore of DBGDTRTX_EL0. It is a component of the Debug Communications Channel.

Configuration

AArch64 System register OSDTRTX_EL1 bits [31:0] are architecturally mapped to AArch32 System register DBGDTRTXext[31:0] .

Attributes

OSDTRTX_EL1 is a 64-bit register.

Field descriptions

The OSDTRTX_EL1 bit assignments are:

6362616059585756555453525150494847464544434241403938373635343332
RES0
Return DTRTX without side-effect
313029282726252423222120191817161514131211109876543210

Bits [63:32]

Reserved, RES0.

Bits [31:0]

Return DTRTX without side-effect.

Reads of this register return the value in DTRTX and do not change TXfull.

Writes of this register update the value in DTRTX and do not change TXfull.

For the full behavior of the Debug Communications Channel, see 'The Debug Communication Channel and Instruction Transfer Register' in the Arm® Architecture Reference Manual, Armv8, for Armv8-A architecture profile, chapter H4.

Accessing the OSDTRTX_EL1

Arm deprecates reads and writes of OSDTRTX_EL1 when the OS Lock is unlocked.

Accesses to this register use the following encodings:

MRS <Xt>, OSDTRTX_EL1

op0op1CRnCRmop2
0b100b0000b00000b00110b010
if PSTATE.EL == EL0 then
    UNDEFINED;
elsif PSTATE.EL == EL1 then
    if EL2Enabled() && !ELUsingAArch32(EL2) && MDCR_EL2.TDCC == '1' then
        AArch64.SystemAccessTrap(EL2, 0x18);
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && MDCR_EL2.<TDE,TDA> != '00' then
        AArch64.SystemAccessTrap(EL2, 0x18);
    elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TDCC == '1' then
        AArch64.SystemAccessTrap(EL3, 0x18);
    elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TDA == '1' then
        AArch64.SystemAccessTrap(EL3, 0x18);
    else
        return OSDTRTX_EL1;
elsif PSTATE.EL == EL2 then
    if HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TDCC == '1' then
        AArch64.SystemAccessTrap(EL3, 0x18);
    elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TDA == '1' then
        AArch64.SystemAccessTrap(EL3, 0x18);
    else
        return OSDTRTX_EL1;
elsif PSTATE.EL == EL3 then
    return OSDTRTX_EL1;
              

MSR OSDTRTX_EL1, <Xt>

op0op1CRnCRmop2
0b100b0000b00000b00110b010
if PSTATE.EL == EL0 then
    UNDEFINED;
elsif PSTATE.EL == EL1 then
    if EL2Enabled() && !ELUsingAArch32(EL2) && MDCR_EL2.TDCC == '1' then
        AArch64.SystemAccessTrap(EL2, 0x18);
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && MDCR_EL2.<TDE,TDA> != '00' then
        AArch64.SystemAccessTrap(EL2, 0x18);
    elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TDCC == '1' then
        AArch64.SystemAccessTrap(EL3, 0x18);
    elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TDA == '1' then
        AArch64.SystemAccessTrap(EL3, 0x18);
    else
        OSDTRTX_EL1 = X[t];
elsif PSTATE.EL == EL2 then
    if HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TDCC == '1' then
        AArch64.SystemAccessTrap(EL3, 0x18);
    elsif HaveEL(EL3) && !ELUsingAArch32(EL3) && MDCR_EL3.TDA == '1' then
        AArch64.SystemAccessTrap(EL3, 0x18);
    else
        OSDTRTX_EL1 = X[t];
elsif PSTATE.EL == EL3 then
    OSDTRTX_EL1 = X[t];
              


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