[libre-riscv-dev] uniform instruction format
Luke Kenneth Casson Leighton
lkcl at lkcl.net
Sun Jun 23 18:43:31 BST 2019
Someone named EricP spotted something, suggested an idea that was basically
equivalent to uepc and a bit more.
This caused me to review the handling of STATE in user mode traps and I
realised we need STATE, ueSTATE, seSTATE and meSTATE.
These to be swapped around a bit on traps, including u mode ones.
It actually reduces the number of CSRs, as an M Mode S Mode VL and MVL and
SUBVL are no longer needed.
crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68
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