From: lkcl Date: Wed, 22 Apr 2020 22:14:14 +0000 (+0100) Subject: (no commit message) X-Git-Tag: convert-csv-opcode-to-binary~2821 X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=e8b82b390676659cef45916f2d894f8b0bd73b5c;p=libreriscv.git --- diff --git a/openpower/isans_letter.mdwn b/openpower/isans_letter.mdwn index 6a16c91b4..b405b4820 100644 --- a/openpower/isans_letter.mdwn +++ b/openpower/isans_letter.mdwn @@ -1,9 +1,9 @@ - # Letter regarding ISAMUX / NS * Revision 0.0 draft: 03 Mar 2020 * Revision 0.1 addw review: 16 Apr 2020 * Revision 0.9 pre-final: 18 Apr 2020 +* Revision 0.91 mention dual ISA: 22 Apr 2020 ## Why has Libre-SOC chosen PowerPC ? @@ -131,6 +131,8 @@ Therefore, to meet our business objectives: toolchains, but also entire GNU/Linux Distros, is highly undesirable, and completely impractical (we know for certain that Redhat would strongly object to any efforts to hard-fork Fedora) +* We could invent our own custom GPU instruction set (or use and extend an existing one, to save a man-decade on toolchain development) however even to switch over to that "Dual ISA" GPU instruction set in the next clock cycle *still requires a PCR modeswitch bit* in order to avoid needing a full Inter-Processor Bus Architecture like on "traditional" GPUs. +* If extending any instruction set, rather than have a Dual ISA (which needs the PCR modeswitch bit to access it) we would rather extend POWER. * We cannot "go ahead anyway" because to do so would be highly irresponsible and cause massive disruption to the POWER community.