The MIDR_EL1 characteristics are:
- Provides identification information for the processor, including an
implementer code for the device and a device ID number.
- Usage constraints
The accessibility to the MIDR_EL1 by Exception
||EL3(SCR.NS = 1)
||EL3(SCR.NS = 0)
The external debug accessibility to the MIDR by condition code
The MIDR_EL1 is:
- Common to Secure and Non-secure states.
- Architecturally mapped to the AArch32 MIDR register.
- Architecturally mapped to external MIDR register.
The following figure shows the MIDR_EL1 bit assignments.
Figure 4-1 MIDR_EL1 bit assignments
The following table shows the MIDR_EL1 bit assignments.
Table 4-16 MIDR_EL1 bit assignments
Indicates the implementer code.
This value is:
- ARM Limited.
Indicates the variant number of
the processor. This is the major revision number
n in the r
n part of the r
n description of
the product revision status. This value is:
- Major revision number.
Indicates the architecture code.
This value is:
- Defined by CPUID scheme.
||Primary part number
Indicates the primary part
number. This value is:
- Cortex-A57 processor.
Indicates the minor revision
number of the processor. This is the minor revision number
n in the p
of the r
n description of the product revision status. This value is:
- Minor revision number.
To access the MIDR_EL1 in AArch64 state, read the register with:
MRS <Xt>, MIDR_EL1; Read Main ID Register
To access the MIDR in AArch32 state, read the CP15 register with:
MRC p15, 0, <Rt>, c0, c0, 0; Read Main ID Register
The MIDR can be accessed through the memory-mapped interface and the
external debug interface, offset