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Why do we disable interrupts at the very start of start(), but only disable the FPU at the start of C ? To start with, doesn't OpenSBI have a starting ABI spec?  What does that say on the matter of the enablement of these features on entry into the environment? Either way, my gut feeling is that these disables (if necessary to begin with) should be together, rather than split like this. That aside, while I can see the value of checking this now, won't we have to delete this again in order to allow for context switching a vCPUs FPU register state? ~Andrew