Renode Tier-2 Linux boot on the eliza-e1 CPU variant

This recipe proves that our platform contract (sw/platform/e1_platform_contract.json, section e1_chip_cpu_variant) is sufficient to boot a real Linux + busybox userspace under Renode — no RTL or FPGA required.

What this branch produced

Path	Purpose
`sim/renode/eliza_e1.repl`	Renode platform model — UART @ 0x10001000, PLIC @ 0x0C000000, CLINT @ 0x02000000, DRAM @ 0x80000000 (256 MiB), DMA/NPU/display stubs at the contract addresses.
`sim/renode/eliza_e1_tier2.resc`	Boot script: loads `fw_payload.elf` (OpenSBI + kernel) and starts the machine, attaching the analyzer to `uart0`.
`sim/renode/eliza_e1_tier2.robot`	Robot test — waits for `eliza tier2: linux booted` and the `/ #` busybox prompt within 60 s.
`scripts/sim/run_renode_tier2.sh`	Wrapper: runs `renode-test` and tees to `build/sim/renode/tier2.log`.
`sw/opensbi/platform/eliza/{platform.c,objects.mk,config.mk,README.md}`	OpenSBI platform glue for our addresses — to be copied into the OpenSBI source tree before building.

Reproducing end-to-end

Inputs from the ws/boot-tier2-linux-busybox worktree:

external/linux/arch/riscv/boot/Image — riscv64 kernel (rv64gc), with the init script printing eliza tier2: linux booted before spawning busybox sh.
build/initramfs/eliza_tier2.cpio.gz — busybox rootfs.

Build OpenSBI for our platform (host: any RISC-V GCC, e.g. riscv64-unknown-elf-gcc):

cp -r sw/opensbi/platform/eliza external/opensbi/platform/
make -C external/opensbi PLATFORM=eliza \
    FW_PAYLOAD_PATH=$(pwd)/external/linux/arch/riscv/boot/Image

Run the smoke:

./scripts/sim/run_renode_tier2.sh

Expected console (in build/sim/renode/tier2.log):

OpenSBI v...
Platform Name             : eliza-e1-cpu-variant
Platform Features         : ...
Platform HART Count       : 1
Boot HART ID              : 0
Firmware Base             : 0x80000000
...
[    0.000000] Linux version ...
[    0.xxxxxx] Console: ttyS0 at MMIO 0x10001000 (irq = 1)
eliza tier2: linux booted
/ #

Current status on this worktree

Renode CLI is installed (/opt/homebrew/bin/renode, /opt/homebrew/bin/renode-test). The .repl / .resc / .robot files and the OpenSBI platform sources are committed. The build inputs (fw_payload.elf, kernel Image, initramfs .cpio.gz) are produced on the sibling ws/boot-tier2-linux-busybox branch and were not present in this worktree at scaffold time, so an end-to-end run has not been executed here. Re-run ./scripts/sim/run_renode_tier2.sh after merging ws/boot-tier2-linux-busybox and building OpenSBI as above.

Why these addresses

All addresses come from sw/platform/e1_platform_contract.json :: e1_chip_cpu_variant. The contract is the single source of truth shared by RTL decode, the kernel DTS, U-Boot, OpenSBI, and the AOSP HAL. This Renode model deliberately does not use QEMU virt addresses (UART at 0x10000000) — it uses our 0x10001000 — so a successful boot on this model is positive evidence that our contract is internally consistent and Linux-bootable.