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clarification on entropy source accesss in vs/vu modes #141

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merged 1 commit into from
Nov 12, 2021
Merged

clarification on entropy source accesss in vs/vu modes #141

merged 1 commit into from
Nov 12, 2021

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mjosaarinen
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@mjosaarinen mjosaarinen commented Nov 10, 2021

Further changes the behavior of VS/VU modes so that a virtual instruction exception is raised only for read-write accesses when mseccfg.sseed=1. Thanks to John Hauser for the clarification. Hopefully closes #139

VS and VU always raises an exception; a read-only instruction causes an
illegal instruction exception, while a read-write instruction (that can
potentially be emulated) causes a virtual instruction exception only if
`mseccfg.seed=1`. Note that `mseccfg.useed` has no effect on the exception
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mseccfg.seed=1 should be mseccfg.sseed=1, no?

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Yes, of course. Fixed now I think.

@ben-marshall ben-marshall merged commit 06ce13a into riscv:master Nov 12, 2021
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Access to seed CSR from VS/VU modes
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