Add slides for 26 Sept meeting

meetings/2024-09-26-slides.md

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+---
+title: "Composable Custom Extensions TG Meeting"
+author: Darius Rad `<darius@bluespec.com>`$\newline$Jan Gray `<jan@fpga.org>`
+date: 26 September 2024
+output: beamer_presentation
+theme: "Warsaw"
+---
+
+## Disclosures
+
+<https://wiki.riscv.org/display/HOME/Meeting+Disclosures>
+
+## Agenda
+
+- Final charter review status
+- Requirements discussion status
+- Draft ratification plan
+- Ad-hoc meeting recap (opcodes)
+
+## Final charter review status
+
+###
+
+Reuse of multiple custom extensions is rare, in part because custom
+extensions may conflict in use of custom instructions and CSRs, and
+because there is no common programming model or API for custom
+extensions. This can lead to disjoint solution silos and ecosystem
+fragmentation. To help address this gap, the TG will advance interop
+standards that make it easier to reuse certain kinds of custom
+extensions, enabling a plug-and-play ecosystem of such extensions.
+
+The TG will define a framework of ISA and non-ISA specifications that
+together facilitate the decentralized, cooperative reuse of the custom
+instruction and custom CSR space, enabling practical reuse, within a
+system, of multiple, independently authored composable custom extensions
+(CXs), CX libraries, and CX unit (CXU) logic modules, while also remaining
+backwards compatible with legacy custom extensions.
+
+###
+
+- Please raise any issues soon
+
+## Requirements discussion status
+
+- Discussion on list
+- Major topics of discussion
+ - Extension state (one/many, hart state or not)
+ - Opcodes (all custom opcodes or subset, one/multiple ranges)
+ - Hotpluggable extensions
+ - Logic interface capabilities
+
+## Draft ratification plan
+
+- Requirements → work breakdown structure → freeze date
+- Work breakdown structure in repository, discussion to begin soon
+
+## Ad-hoc meeting recap (opcodes)
+
+- No consensus reached, no decisions made
+- There was some question about opcode usage in existing legacy custom extensions
+ - Which major custom opcodes are in use
+ - How may opcodes are used by each custom extension
+ - Might be worth a survey to collect data, if can be done in a timely fashion
+- Requirements regarding handling legacy custom extensions may need to be refined