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riscv / riscv-aia

https://jira.riscv.org/browse/RVG-59
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regarding holes in idc structures #9

Closed neelgala closed 2 years ago

neelgala commented 2 years ago

The idc structures requires 32-bytes but fields for only 20 bytes have been allocated. Are the other 12-bytes reserved or available for custom use? Should they be read-only zeros if accessed or should we raise a bus/slave error?

jhauser-us commented 2 years ago

The intro to section 4.5, "Memory-mapped control region for an interrupt domain", says:

Aside from the registers in Table 4.1 and those listed above for IDC structures, all other bytes in an interrupt domain’s control region are reserved and are implemented as read-only zeros.

If there is a need to designate some of that space for custom use, it could be done. But currently, all of the unallocated 12 bytes are reserved for future standards; they can't be custom.

neelgala commented 2 years ago

thanks.