= Composable Custom Extensions Developement Plan =
This file captures the work items for the Composable Custom Extensions Task Group in a work breakdown structure (WBS) [1].
[1] https://en.wikipedia.org/wiki/Work_breakdown_structure
Tasks must follow the principles of a WBS:
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Any, and varying, levels of hierarchy are allowed. Only leaf elements in the hierarchy represent work to be done. Thus, only leaf elements have time estimates, dependencies, owners, etc., assigned to them.
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Every task is only captured in a single place; nothing is duplicated.
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Non-leaf elements can be considered as the sum of all leaf items with respect to time estimates, dependencies, etc.
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Time estimates are three point estimates (optimistic, expected, and pessimistic).
This file is intended to be machine readable with ad-hoc tooling.
Time estimates are work time; scheduling will be done separately. For estimating purposes, one day (1d) is eight hours (8h), one week (1w) is five days, and one month (1m) is four weeks.
spec Specifications spec-isa ISA Specification Package spec-isa-priv privileged opcode and state multiplexing dep=none owner=[email protected] [8w, 10w, 12w] progress=0%
Specify an ISA extension for more privileged code to grant access to a CX to less privileged code, and to enable privileged code to trap and emulate CX instructions/CSRs.
If necessary the ISA extension also supports access control to multiple CX instances of the same CX.
spec-isa-unpriv unprivileged opcode and state multiplexing [5w, 7w, 10w]
Specify an ISA extension to select the current CX to perform custom instructions/CSRs, and to indicate multiplexing status/errors.
If necessary the ISA extension supports selection of one of possibly multiple CX instances of the same CX.
If necessary the ISA extension also supports selection of a current CX (or CX instance) for each of multiple subranges of custom instructions/CSRs.
spec-isa-state privileged state management [3w, 4w, 6w]
Specify an ISA extension to uniformly initialize, save, and restore any CX state context.
spec-criteria Composability criteria
Specify criteria for a composable custom extension.
spec-criteria-ext Basic composability criteria [1w, 3w, 4w]
Specify basic criteria for a custom extension to be deemed a composable custom extension, excluding any behavior for accessing memory.
spec-criteria-mem Composable memory access behavior [1w, 3w, 4w]
Specify a portable memory model for composable custom extensions.
spec-disc Discovery spec-disc-ud Unified Discovery [2w, 4w, 8w]
Add schema for identifying composable custom extension on harts and any necessary parameters, such as state size.
If necessary add schema for identifying multiple CX instances and heterogeneous per-hart accessibility of these CX instances.
spec-disc-dt Devicetree [2w, 4w, 8w]
Add schema for attributes that identify composable custom extension on harts and any necessary parameters, such as state size.
If necessary add schema for identifying multiple CX instances and heterogeneous per-hart accessibility of these CX instances.
spec-disc-acpi ACPI [4w, 6w, 8w]
Add definition for ACPI table for identifying composable custom extension on harts and any necessary parameters, such as state size.
If necessary add support for identifying multiple CX instances and heterogeneous per-hart accessibility of these CX instances.
spec-sbi SBI extension [0d, 0d, 0d]
It is unclear if an SBI extension is necessary. It will be specified as needed.
spec-linux Linux syscall [4w, 6w, 8w]
Add interfaces to hwprobe, prctl, and sysfs to provide discovery of composable custom extensions and related parameters and control of extension enablement.
If necessary add additional interfaces or syscalls to support a multiple CX instance model.
spec-abi User space ABI spec-abi-cx Composable custom extension aware calling convention [4w, 6w, 8w]
Define a calling convention for handling composable custom extension framework state on calls between object files that both support this convention.
Define criteria for use by composable custom extension authors in defining extension specific calling conventions that support similar behavior.
spec-abi-legacy Legacy interoperability calling convention [4w, 6w, 8w]
Define calling conventions for handling composable custom extension framework state on calls between object files that support composable custom extensions (as defined in spec-abi-cx) and those that do not.
Define criteria for use by composable custom extension authors in defining extension specific calling conventions that support similar behavior.
spec-uapi User space API [2w, 6w, 9w]
Specify an API that provides a uniform CX programming model including CX naming, discovery, versioning, CX selection, and error handling and correct composition of CX libraries.
If necessary the API will support both the singleton CX model and the multiple CX instance model.
spec-li Logic interface [8w, 12w, 16w]
Specify a logic signal level interface for composable custom extensions.
rv ISA Specification support rv-test RISC-V Test Input []
Test configuration input
rv-sail SAIL model rv-sail-priv privileged opcode and state multiplexing dep=spec-isa-priv []
Implement SAIL support for the privileged opcode and state multiplexing features of the ISA.
rv-sail-unpriv unprivileged opcode and state multiplexing dep=spec-isa-unpriv []
Implement SAIL support for the unprivileged opcode and state multiplexing features of the ISA.
rv-sail-state privileged state management dep=spec-isa-state []
Implement SAIL support for the privileged state management features of the ISA.
rv-act Architecture Compliance Tests (ACT)
All compliance tests should test basic functionality and need not be complete verification tests that cover all corner cases.
rv-act-priv privileged opcode and state multiplexing dep=spec-isa-priv [2w, 3w, 4w]
Implement compliance tests for the privileged opcode and state multiplexing features of the ISA.
rv-act-unpriv unprivileged opcode and state multiplexing dep=spec-isa-unpriv [8d, 2w, 3w]
Implement compliance tests for the unprivileged opcode and state multiplexing features of the ISA.
rv-act-state privileged state management dep=spec-isa-state [8d, 2w, 3w]
Implement compliance tests for the privileged state management features of the ISA.
sw Software ecosystem support sw-opensbi OpenSBI support dep=spec-sbi [0d, 0d, 0d]
Implement the specified SBI extension in OpenSBI.
sw-linux Linux support sw-linux-dt Devicetree configuration dep=spec-disc-dt [1w, 8d, 2w]
Add support to Linux for obtaining the composable custom extension configuration from the specified devicetree attributes.
sw-linux-acpi ACPI configuration dep=spec-disc-acpi [8d, 2w, 3w]
Add support to Linux for obtaining the composable custom extension configuration from the specified ACPI table.
sw-linux-state Context save and restore dep=spec-isa-state [6w, 8w, 10w]
Add support to Linux for managing composable custom extension framework state and extension state, including saving and restoring state on context switch, allocating memory for state efficiently, and reporting errors.
If necessary add additional support for a multiple CX instance model.
sw-linux-uabi Linux User Space ABI dep=spec-linux [4w, 6w, 10w]
Add support to Linux for specified the user space ABI, including hwprobe, prctl, and sysfs support. Add documentation and self tests as appropriate.
If necessary add additional support for a multiple CX instance model.
sw-baremetal Bare metal software support [0d, 0d, 0d]
Bare metal software support is not planned.
sw-rtos Real time operating system support [0d, 0d, 0d]
Real time operating system support is not planned.
sw-abi User space ABI sw-abi-binutils binutils support dep=spec-abi-cx,spec-abi-legacy [3w, 4w, 6w]
Add support for managing the specified ABI variants to RISC-V ELF files, including support in ld, readelf, and objdump.
Add support to assembler and disassembler for new opcodes, as needed.
sw-abi-gcc gcc support dep=spec-abi-cx,spec-abi-legacy [2w, 3w, 5w]
Add support for saving and restoring composable custom extension framework state. Add support for managing the appropriate ABI variants in RISC-V ELF files.
Add instrinsics for new opcodes, as needed.
sw-abi-glibc glibc support dep=spec-abi [2w, 4w, 8w]
Handle user visible framework hart state as necessary, including in setcontext/makecontext and setjmp/longjmp.
If necessary add additional support for a multiple CX instance model.
sw-uapi User space API sw-uapi-glibc glibc support dep=spec-linux,spec-uapi [2w, 4w, 8w]
Add wrappers in glibc for the specified Linux hwprobe and/or prctl functions.
poc Proof of concept poc-qemu QEMU model poc-qemu-isa ISA support poc-qemu-isa-priv privileged opcode and state multiplexing dep=spec-isa-priv [4w, 8w, 10w]
Implement a model of the privileged opcode and state multiplexing features of the ISA.
poc-qemu-isa-unpriv unprivileged opcode and state multiplexing dep=spec-isa-unpriv [4w, 6w, 10w]
Implement a model of the unprivileged opcode and state multiplexing features of the ISA.
poc-qemu-isa-state privileged state management dep=spec-isa-state [2w, 3w, 5w]
Implement a model of the privileged state management features of the ISA.
poc-qemu-sampleext Sample extension [1w, 2w, 3w]
Implement a model of a sample composable custom extension that provides all necessary interface with framework and a simple noop function.
poc-hw Hardware implementation poc-hw-isa ISA support poc-hw-isa-priv privileged opcode and state multiplexing dep=spec-isa-priv [4w, 8w, 10w]
Implement the privileged opcode and state multiplexing features of the ISA in hardware.
poc-hw-isa-unpriv unprivileged opcode and state multiplexing dep=spec-isa-unpriv [4w, 6w, 10w]
Implement the unprivileged opcode and state multiplexing features of the ISA in hardware.
poc-hw-isa-state privileged state management dep=spec-isa-state [2w, 3w, 5w]
Implement the privileged state management features of the ISA in hardware.
poc-hw-li Logic interface dep=spec-li [2w, 4w, 6w]
Implement the logic level interface to a processor in hardware.
poc-hw-sampleext Sample extension dep=spec-li [2w, 3w, 5w]
Implement a sample composable custom extension that provides all necessary interface with framework and a simple noop function.
poc-sampleapp Sample application dep=spec-uapi [2w, 3w, 4w]
Implement the software for a sample application that exercises the basic framework functions and a noop extension function.
poc-int Integration testing poc-int-qemu QEMU model integration testing dep=sw,poc-qemu,poc-sampleapp [6w, 8w, 20w]
Combine completed system software, QEMU model, and application software; test and debug.
poc-int-hw Hardware implementation integration testing dep=sw,poc-hw,poc-sampleapp [6w, 8w, 20w]
Combine completed system software, hardware implementation, and application software; test and debug.
freeze Ratification Plan Freeze Milestone
The sub tasks here represent the tasks on the ratification plan checklist for the freeze milestone. These are dependency tasks with no real work and reflect dependencies on other tasks.
freeze-isa ISA Freeze Checklist freeze-isa-opcode Opcode Support dep=sw-abi-gcc [0d, 0d, 0d]
Enough opcode encoding to support GCC.
freeze-isa-sim Simulator Support dep=poc-qemu [0d, 0d, 0d]
Enough simulator support so that basic RISC-V tests can be run.
freeze-isa-psabi psABI dep=spec-abi [0d, 0d, 0d]
ABI extensions.
freeze-isa-gcc gcc dep=sw-abi [0d, 0d, 0d]
Support on GCC (optimizations not required).
freeze-isa-llvm llvm [0d, 0d, 0d]
Support on LLVM (optimizations not required). [not planned]
freeze-isa-rvtestinput RISC-V Test Input dep=rv-test [0d, 0d, 0d]
Test configuration input (YAML schema & values, Test Coverage YAML rules).
freeze-isa-rvtest RISC-V Tests dep=rv-act [0d, 0d, 0d]
Basic tests that do not cover corner cases.
freeze-isa-rvsail RISC-V SAIL dep=rv-sail [0d, 0d, 0d]
SAIL support.
freeze-nonisa Non-ISA Freeze Checklist freeze-nonisa-opensbi OpenSBI dep=sw-opensbi [0d, 0d, 0d]
Discovery and configuration. [as needed]
freeze-nonisa-linux Linux dep=sw-linux [0d, 0d, 0d]
Discovery and configuration, context management, access control.
freeze-nonisa-glibc glibc dep=sw-uapi [0d, 0d, 0d]
Discovery and configuration, user context management.