The ICC_SRE_EL3 characteristics are:
Controls whether the System register interface or the memory-mapped interface to the GIC CPU interface is used for EL3.
This register is part of:
AArch64 System register ICC_SRE_EL3 can be mapped to AArch32 System register ICC_MSRE, but this is not architecturally mandated.
ICC_SRE_EL3 is a 32-bit register.
The ICC_SRE_EL3 bit assignments are:
31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | Enable | DIB | DFB | SRE |
Reserved, RES0.
Enable. Enables lower Exception level access to ICC_SRE_EL1 and ICC_SRE_EL2.
Enable | Meaning |
---|---|
0 |
Secure EL1 accesses to Secure ICC_SRE_EL1 trap to EL3. EL2 accesses to Non-secure ICC_SRE_EL1 and ICC_SRE_EL2 trap to EL3. Non-secure EL1 accesses to ICC_SRE_EL1 trap to EL3, unless these accesses are trapped to EL2 as a result of ICC_SRE_EL3.Enable == 0. |
1 |
Secure EL1 accesses to Secure ICC_SRE_EL1 do not trap to EL3. EL2 accesses to Non-secure ICC_SRE_EL1 and ICC_SRE_EL2 do not trap to EL3. Non-secure EL1 accesses to ICC_SRE_EL1 do not trap to EL3. |
If ICC_SRE_EL3.SRE is RAO/WI, an implementation is permitted to make the Enable bit RAO/WI.
If ICC_SRE_EL3.SRE is 0, the Enable bit behaves as 1 for all purposes other than reading the value of the bit.
Disable IRQ bypass.
DIB | Meaning |
---|---|
0 |
IRQ bypass enabled. |
1 |
IRQ bypass disabled. |
In systems that do not support IRQ bypass, this bit is RAO/WI.
When this register has an architecturally-defined reset value, if this field is implemented as an RW field, it resets to 0.
Disable FIQ bypass.
DFB | Meaning |
---|---|
0 |
FIQ bypass enabled. |
1 |
FIQ bypass disabled. |
In systems that do not support FIQ bypass, this bit is RAO/WI.
When this register has an architecturally-defined reset value, if this field is implemented as an RW field, it resets to 0.
System Register Enable.
SRE | Meaning |
---|---|
0 |
The memory-mapped interface must be used. Access at EL3 to any ICH_* or ICC_* register other than ICC_SRE_EL1, ICC_SRE_EL2, or ICC_SRE_EL3 is trapped to EL3 |
1 |
The System register interface to the ICH_* registers and the EL1, EL2, and EL3 ICC_* registers is enabled for EL3. |
If software changes this bit from 1 to 0, the results are UNPREDICTABLE.
GICv3 implementations that do not require GICv2 compatibility might choose to make this bit RAO/WI.
When this register has an architecturally-defined reset value, if this field is implemented as an RW field, it resets to 0.
This register can be read using MRS with the following syntax:
MRS <Xt>, <systemreg>
This register can be written using MSR (register) with the following syntax:
MSR <systemreg>, <Xt>
This syntax uses the following encoding in the System instruction encoding space:
<systemreg> | op0 | op1 | CRn | CRm | op2 |
---|---|---|---|---|---|
ICC_SRE_EL3 | 11 | 110 | 1100 | 1100 | 101 |
The register is accessible as follows:
Control | Accessibility | ||||
---|---|---|---|---|---|
TGE | NS | EL0 | EL1 | EL2 | EL3 |
x | 0 | - | - | n/a | RW |
0 | 1 | - | - | - | RW |
1 | 1 | - | n/a | - | RW |
This table applies to all instructions that can access this register.
This register is always System register accessible.
For a description of the prioritization of any generated exceptions, see section D1.13.2 (Synchronous exception prioritization) in the ARM® Architecture Reference Manual, ARMv8, for ARMv8-A architecture profile. Subject to the prioritization rules, the following traps and enables are applicable when accessing this register.
When EL2 is implemented and is using AArch64 and SCR_EL3.NS==1 :
If HSTR_EL2.T12==1, Non-secure accesses to this register from EL1 are trapped to EL2.
When EL2 is implemented and is using AArch64 and SCR_EL3.NS==1 :
If ICC_SRE_EL2.Enable==0, Non-secure accesses to this register from EL1 are trapped to EL2.
When EL2 is implemented and is using AArch64 and SCR_EL3.NS==1 && HCR_EL2.TGE==0 :
If HSTR_EL2.T12==1, Non-secure accesses to this register from EL1 are trapped to EL2.
When EL3 is implemented and is using AArch64 :
If ICC_SRE_EL3.Enable==0, accesses to this register from EL2 are trapped to EL3.
28/09/2017 08:24
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