Hi Amit,
Refer to Arm ARM [1] section D23.2.155 "FIEN, bit [21] is present if FEAT_RASv1p1 is implemented otherwise RES0"
On the page A2-119 In an Armv8.4 implementation, if FEAT_RAS is implemented, FEAT_RASv1p1 is implemented. FEAT_RASv1p1 is OPTIONAL from Armv8.2. Again on page A2-104, FEAT_RAS is mandatory from Armv8.2
Coming to Cortex-A78 [2], it is based on 8.2 and it has fault injection support(section 2.8.7) Reason for no details of SCR in CPU TRMs is becasue it should be read in conjunction with Arm ARM
[1]: https://developer.arm.com/documentation/ddi0487/latest/ [2]: https://developer.arm.com/documentation/101430/latest/
Thanks Manish Pandey ________________________________ From: Nagal, Amit via TF-A tf-a@lists.trustedfirmware.org Sent: 08 May 2024 10:15 To: tf-a@lists.trustedfirmware.org tf-a@lists.trustedfirmware.org Subject: [TF-A] FAULT_INJECTION_SUPPORT - FIEN bit
Hi,
Referring https://github.com/ARM-software/arm-trusted-firmware/blob/master/docs/gettin... it says : ``FAULT_INJECTION_SUPPORT``: ARMv8.4 extensions introduced support for fault injection from lower Els.
Referring https://github.com/ARM-software/arm-trusted-firmware/blob/master/lib/el3_run... FAULT_INJECTION_SUPPORT enables FIEN bit. #if FAULT_INJECTION_SUPPORT /* Enable fault injection from lower ELs */ scr_el3 |= SCR_FIEN_BIT; #endif
Question : 1. Do we have any relevant documentation from arm which specifies FIEN bit can be enabled from armv8.4 ?
2. In cortex a-53 technical reference manual, SCR_EL3 does not have FIEN bit , bit 21 is marked reserved . In cortex a-78 technical reference manual , manual does not have details for SCR_EL3 . I want to know whether on Armv8.2-a based cores like cortex a-78 , is the FIEN bit field marked reserved in SCR_EL3 register or is available functionality wise as in armv8.4 ? Please help with above query.
Regards Amit
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