From: Luke Kenneth Casson Leighton Date: Sat, 1 Apr 2023 19:58:56 +0000 (+0100) Subject: clarify reserved areas X-Git-Tag: opf_rfc_ls012_v1~188 X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=e38812c9b468349dbe37c404a39cd4a79cf72cbc;p=libreriscv.git clarify reserved areas --- diff --git a/openpower/sv/rfc/Makefile b/openpower/sv/rfc/Makefile index 2c58d4968..8771c275b 100644 --- a/openpower/sv/rfc/Makefile +++ b/openpower/sv/rfc/Makefile @@ -11,6 +11,7 @@ all: ls001.pdf ls002.pdf ls003.pdf ls004.pdf ls005.pdf ls006.pdf ls007.pdf -V linkcolor=blue \ -f markdown $*.mdwn \ -s --self-contained \ + --mathjax \ -o $*.pdf upload: diff --git a/openpower/sv/rfc/ls010.mdwn b/openpower/sv/rfc/ls010.mdwn index 78f501777..7301f9dfb 100644 --- a/openpower/sv/rfc/ls010.mdwn +++ b/openpower/sv/rfc/ls010.mdwn @@ -449,16 +449,27 @@ Encoding spaces and their potential are illustrated: | Encoding | Available bits | Scalar | Vectoriseable | SVP64Single | |----------|----------------|--------|---------------|--------------| |EXT000-063| 32 | yes | yes |yes | -|EXT100-163| 64 (?) | yes | no |no | -|RESERVED2 | 57 | N/A |not applicable |not applicable| +|EXT100-163| 64 | yes | no |no | +|R3SERVED2 | 57 | N/A |not applicable |not applicable| |EXT232-263| 32 | yes | yes |yes | |RESERVED1 | 32 | N/A | no |no | -Prefixed-Prefixed (96-bit) instructions are prohibited. RESERVED2 presently -remains unallocated as of yet and therefore its potential is not yet defined -(Not Applicable). RESERVED1 is also unallocated at present, but it is -known in advance that the area is UnVectoriseable and also cannot be -Prefixed with SVP64Single. +Notes: + +* Prefixed-Prefixed (96-bit) instructions are prohibited. EXT1xx is + thus inherently UnVectoriseable as the EXT1xx prefix is 32-bit + on top of an SVP64 prefix which is 32-bit on top of a Defined Word + and the complexity at the Decoder becomes too great for High + Performance Multi-Issue systems. +* RESERVED2 presently remains unallocated as of yet and therefore its + potential is not yet defined (Not Applicable). +* RESERVED1 is also unallocated at present, but it is known in advance + that the area is UnVectoriseable and also cannot be Prefixed with + SVP64Single. +* Considerable care is needed both on Architectural Resource Allocation + as well as instruction design itself. Once an instruction is allocated + in an UnVectoriseable area it can never be Vectorised without providing + an entirely new Encoding. # Remapped Encoding (`RM[0:23]`)