TRBMAR_EL1: Trace Buffer Memory Attribute Register

Reserved, RES0.

Physical address specifier. Defines the PAS attribute for memory addressed by the buffer in External mode.

PAS	Meaning	Applies when
0b00	Secure.	When Secure state is implemented
0b01	Non-secure.
0b10	Root.	When FEAT_RME is implemented
0b11	Realm.	When FEAT_RME is implemented

All other values are reserved.

If the Trace Buffer Unit is using external mode and either TRBMAR_EL1.PAS is set to a reserved value, or the IMPLEMENTATION DEFINED authentication interface prohibits invasive debug of the Security state corresponding to the physical address space selected by TRBMAR_EL1.PAS, then when the Trace Buffer Unit receives trace data from the trace unit, it does not write the trace data to memory and generates a trace buffer management event. That is, if any of the following apply:

• ExternalInvasiveDebugEnabled() == FALSE.
• Secure state is implemented, ExternalSecureInvasiveDebugEnabled() == FALSE, and TRBMAR_EL1.PAS is 0b00.
• FEAT_RME is implemented, ExternalRootInvasiveDebugEnabled() == FALSE, and TRBMAR_EL1.PAS is 0b10.
• FEAT_RME is implemented, ExternalRealmInvasiveDebugEnabled() == FALSE, and TRBMAR_EL1.PAS is 0b11.

This field is ignored by the PE when SelfHostedTraceEnabled() == TRUE.

The reset behavior of this field is:

• On a Cold reset, this field resets to an architecturally UNKNOWN value.

Reserved, RES0.

Trace buffer shareability domain. Defines the shareability domain for Normal memory used by the trace buffer.

SH	Meaning
0b00	Non-shareable.
0b10	Outer Shareable.
0b11	Inner Shareable.

All other values are reserved.

This field is ignored when TRBMAR_EL1.Attr specifies any of the following memory types:

• Any Device memory type.
• Normal memory, Inner Non-cacheable, Outer Non-cacheable.

All Device and Normal Inner Non-cacheable Outer Non-cacheable memory regions are always treated as Outer Shareable.

The reset behavior of this field is:

• On a Cold reset, this field resets to an architecturally UNKNOWN value.

Trace buffer memory type and attributes. Defines the memory type and, for Normal memory, the cacheability attributes, for memory addressed by the trace buffer.

Attr	Meaning	Applies when
0x00	Device-nGnRnE memory.
0x40	Normal memory, Inner Non-cacheable, Outer Non-cacheable with the XS attribute set to 0.	When FEAT_XS is implemented
0xA0	Normal memory, Inner Write-through Cacheable, Outer Write-through Cacheable, Non-transient, Read-Allocate with the XS attribute set to 0.	When FEAT_XS is implemented
0xF0	Tagged Normal memory, Outer Write-Back Non-transient, Read-allocate Write-allocate.	When FEAT_MTE2 is implemented

All other values are reserved.

The reset behavior of this field is:

• On a Cold reset, this field resets to an architecturally UNKNOWN value.

Trace buffer memory attributes. Defines the Device memory attributes for memory addressed by the trace buffer.

Attr	Meaning	Applies when
0x04	Device-nGnRE memory.
0x08	Device-nGRE memory.
0x0C	Device-GRE memory.
0x01	Device-nGnRnE memory with the XS attribute set to 0.	When FEAT_XS is implemented
0x05	Device-nGnRE memory with the XS attribute set to 0.	When FEAT_XS is implemented
0x09	Device-nGRE memory with the XS attribute set to 0.	When FEAT_XS is implemented
0x0D	Device-GRE memory with the XS attribute set to 0.	When FEAT_XS is implemented

All other values are reserved.

The reset behavior of this field is:

• On a Cold reset, this field resets to an architecturally UNKNOWN value.

Trace buffer memory type and attributes. Defines the memory type and, for Normal memory, the Outer and Inner cacheability attributes, for memory addressed by the trace buffer.

Attr	Meaning
0b0001xxxx	Normal memory, Outer Write-Through Transient, Write-allocate.
0b0010xxxx	Normal memory, Outer Write-Through Transient, Read-allocate.
0b0011xxxx	Normal memory, Outer Write-Through Transient, Read-allocate Write-allocate.
0b0100xxxx	Normal memory, Outer Non-cacheable.
0b0101xxxx	Normal memory, Outer Write-Back Transient, Write-allocate.
0b0110xxxx	Normal memory, Outer Write-Back Transient, Read-allocate.
0b0111xxxx	Normal memory, Outer Write-Back Transient, Read-allocate Write-allocate.
0b1000xxxx	Normal memory, Outer Write-Through Non-transient, No allocate.
0b1001xxxx	Normal memory, Outer Write-Through Non-transient, Write-allocate.
0b1010xxxx	Normal memory, Outer Write-Through Non-transient, Read-allocate.
0b1011xxxx	Normal memory, Outer Write-Through Non-transient, Read-allocate Write-allocate.
0b1100xxxx	Normal memory, Outer Write-Back Non-transient, No allocate.
0b1101xxxx	Normal memory, Outer Write-Back Non-transient, Write-allocate.
0b1110xxxx	Normal memory, Outer Write-Back Non-transient, Read-allocate.
0b1111xxxx	Normal memory, Outer Write-Back Non-transient, Read-allocate Write-allocate.
0bxxxx0001	Normal memory, Inner Write-Through Transient, Write-allocate.
0bxxxx0010	Normal memory, Inner Write-Through Transient, Read-allocate.
0bxxxx0011	Normal memory, Inner Write-Through Transient, Read-allocate Write-allocate.
0bxxxx0100	Normal memory, Inner Non-cacheable.
0bxxxx0101	Normal memory, Inner Write-Back Transient, Write-allocate.
0bxxxx0110	Normal memory, Inner Write-Back Transient, Read-allocate.
0bxxxx0111	Normal memory, Inner Write-Back Transient, Read-allocate Write-allocate.
0bxxxx1000	Normal memory, Inner Write-Through Non-transient, No allocate.
0bxxxx1001	Normal memory, Inner Write-Through Non-transient, Write-allocate.
0bxxxx1010	Normal memory, Inner Write-Through Non-transient, Read-allocate.
0bxxxx1011	Normal memory, Inner Write-Through Non-transient, Read-allocate Write-allocate.
0bxxxx1100	Normal memory, Inner Write-Back Non-transient, No allocate.
0bxxxx1101	Normal memory, Inner Write-Back Non-transient, Write-allocate.
0bxxxx1110	Normal memory, Inner Write-Back Non-transient, Read-allocate.
0bxxxx1111	Normal memory, Inner Write-Back Non-transient, Read-allocate Write-allocate.

The reset behavior of this field is:

• On a Cold reset, this field resets to an architecturally UNKNOWN value.

Reserved, RES0.