Merge pull request #508 from ChristofPetig/main

Today's eSIG meeting minutes (first version before watching the recording)

SIG-Embedded/2025/01-07-Meeting-notes.md

@@ -33,8 +33,79 @@
 
 ## Notes
 
-* TODO
+* Introduction to memory control:
+
+  The [memory control proposal by Google](https://github.com/WebAssembly/memory-control/)
+  defines e.g. read only memory. 
+  (Note by author virtual mode is likely the one eSIG is looking for because the other sub-proposals are too limited.)
+
+  Luke proposed to use shared memory for zero-copy streams, [probably this link](https://github.com/WebAssembly/component-model/issues/369#issuecomment-2484459838) 
+
+  The core group is currently discussing memory control, Google is preferring 
+  zero hardware requirements.
+
+* [Hardware requirement clarification](https://github.com/bytecodealliance/sig-embedded/issues/7):
+
+  Chris found no hardware with 500kB of RAM which doesn't provide at least an MPU. 
+  Requiring an MMU might be possible as a project requirement. The existence of an
+  RTOS can be assumed.
+
+  The proposed RISC-V chip comes with an MPU like device called PMP, see [this link](https://github.com/bytecodealliance/sig-embedded/issues/7#issuecomment-2574759255)
+
+  On Cortex-M an MPU is optional, but M4/M7 typically provide it, M0 might need special
+  workarounds (CPU cost).
+
+  The [Cyber Resilience Act](https://digital-strategy.ec.europa.eu/en/library/cyber-resilience-act) will likely require sandboxing.
+
+  [Option 5](https://github.com/WebAssembly/memory-control/issues/19) will likely be able
+  to support chips without MMU by a copy and without an MPU by [masking](https://github.com/gwsystems/aWsm)
+
+  Discontinous memory can avoid copying and masking with an MPU might result 
+  in non-conformant sandboxing of the binary (e.g. accesses into the hole might not trap).
+
+* Three phases for shared memory implementation:
+
+  1. Mapping shared memory into an address space of the module
+  2. (?) Implementing subpartitioning of the memory
+  3. Handling mutual access to parts of the memory
+
+* Basically there are two different approaches to shared memory design
+
+  - bottom-up approach: Provide primitives for low level shared memory and work
+    from there. Most likely compatible with existing software design. Equivalent
+    to Option 1 to 4.
+
+  - top-down approach: Provide semantic access to shared memory based on high-level
+    API design. Best for sandboxing and portability. Equivalent to Option 5.
+
+  Option 6 might align well with CHERI hardware capabilities.
+
+  Ayako confirmed that they are currently [going for](https://github.com/bytecodealliance/wasm-micro-runtime/issues/3546) Option 4, because this doesn't 
+  require an MPU. With an MPU native code would be the more performant choice providing
+  similar sandboxing.
+
+  It looks like there is currently no size-fits-all approach within the eSIG.
+
+* Proposal to create a Matrix of options and hardware capabilities.
+
+  - To be clarified: Which axises should span the matrix, Chris will make a proposal
+    and wait for feed-back.
+
+* Interaction with other parts of the community
+
+  - Marcin will discuss multithreading solutions with Andrew Brown later this week.
+
+  - The activation of reftypes by default by the WASI SDK created a portability
+    roadblock, the ability to turn it off requires a nightly Rust compiler.
+
+  - A bridge between WASIp2 for a WASIp1 environment added to the agenda
+    of the next eSIG meeting.
+
+  - [WASI 0.3 is progressing nicely](https://github.com/orgs/bytecodealliance/projects/16), wasm-tools contains the changes, 
+    [wit-bindgen](https://github.com/bytecodealliance/wit-bindgen/pull/1082) is in review phase, [wasmtime](https://github.com/bytecodealliance/wasmtime/pull/9582) is worked on.
+
+    There is already an [early prototype of Streams with native compilation](https://github.com/cpetig/wit-bindgen/tree/main/crates/cpp/tests/symmetric_stream).
 
 ## Action Items
 
-* [ ] TODO
+* [ ] Create Matrix of shared memory requirements