Hello:
Suppose all exception Ievels support both big and little endian operation. According to the ARMv8 ARMARM, when exception taken from AArch32 state, the SPSR_EL1.E bit can control the endianess on executing an exception return operation in EL1, which means it can control the endianess of the EL0, if I am not missing something.
But there is also a contrl register named SCTLR_EL1, and the E0E bit do control the endianness of data accesses at EL0.
I am confused with the SPSR_EL1.E bit and the SCTLR_EL1.E0E bit. If they set the confilct configuration, what will the processer behave? Same with the SCTLR_EL2 and SPSR_EL2...
Regards, George.
Maybe this helps (DDI0487Fc_armv8_arm.pdf D4.3 ):If mixed endian support is implemented for an Exception level using AArch32, endianness is controlled by PSTATE.E. For exception returns to AArch32 state, PSTATE.E is copied from SPSR_ELx.E. If the target Exception level supports only little-endian accesses, SPSR_ELx.E is RES0. If the target Exception level supports only big-endian accesses, SPSR_ELx.E is RES1. PSTATE.E is ignored in AArch64 state.
OK, thanks a lot. It's clear in the Reference Manual.