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Improved clarity regarding xcause when switching between CLIC and CLINT #408

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Sep 17, 2024
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Improved clarity regarding xcause when switching between CLIC and CLINT #408

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14 changes: 7 additions & 7 deletions src/clic.adoc
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Original file line number Diff line number Diff line change
Expand Up @@ -970,13 +970,13 @@ through the trap handling process.
11:0 exccode[11:0] Exception/interrupt code
----

The `mcause.mpp` and `mcause.mpie` fields typically mirror the `mstatus.mpp` and
`mstatus.mpie` fields, and are aliased into `mcause` to reduce context
save/restore code. For backwards compatibility in implementations supporting both CLINT and CLIC modes, when
switching to CLINT mode the new CLIC {cause} state field
({pil}) is zeroed. The other new CLIC {cause} fields,
{pp} and {pie}, appear as zero in the {cause} CSR but the corresponding
state bits in the `mstatus` register are not cleared.
The `mcause.mpp` and `mcause.mpie` fields mirror the `mstatus.mpp` and
`mstatus.mpie` fields when in CLIC mode to reduce context
save/restore code.
Else, these fields read as zero.
For backwards compatibility in implementations supporting both CLINT and CLIC modes, when
switching to CLINT mode the new CLIC {cause}.{pil} state field
is zeroed.

If the hart is currently running at some privilege mode (`pp`) at some
interrupt level (`pil`) and an enabled interrupt becomes pending at
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