BlackMark
8f6319c068
Four cuts, none touching what the loader can do. The entry stub stops re-doing the reset logic's own SP write where the datasheet guarantees RAMEND (stack::hardware — the classic megas keep theirs). The autobaud unit moves into GPIOR2:GPIOR1 wherever the chip has the pair: one-word accesses, no RAM object, and the host's measured-clock peek follows it by version and geometry. 'J' rides the unified decode, carrying a selector it ignores so its address is the same two reads as every other command — the tool sends the bare form to older residents. run_app stops insisting on a body of its own. The fleet lands at 358–410 B stock and 438–474 B autobaud; the tightest image in the space — the 1284s' autobaud on a USART's own pins with the OSCCAL trim — drops from 510 to 484 of its 512. Every chip's suite is green on the wire that changed, and the README's table is machine-checked against the built images. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
78 lines
3.8 KiB
Markdown
78 lines
3.8 KiB
Markdown
# Atmel Studio
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`master` carries `bootloader.atsln`, so this branch does too: `ide/bootloader.atsln`
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builds the loaders from the same sources Ninja does, to a **byte-identical
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`.text`** — 390 B for the 328P pureboot loader, 510 B for the `tsb_asm` tier in
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its 512-byte section. CMake remains the build system; the solution is here so the
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port opens in Studio as its predecessor did.
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## The two projects, and why two
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pureboot is a chip × backend × clock × baud matrix — `pureboot_add_loader()`
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resolves a deployment into compile definitions — and a `.cppproj` is one binary
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at one set of flags, so a project can only ever be one point of it. `pureboot`
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is that point: the stock 328P deployment, USART0 at 115200 on a 16 MHz crystal,
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an 8-second activation window. `tsb_asm` is the TinySafeBoot tier that occupies
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the same 512-byte section `master`'s `tsb` project targeted.
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The other three tsb tiers (`tsb_pure`, `tsb_tricks`, `tsb_policy`) are not here.
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They differ from `tsb_asm` in their source file, their section size, and — for
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`tsb_policy` — two loop flags; nothing about that is a Studio concern, and what
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they exist to demonstrate is a size gradient only the CMake size tests measure.
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Adding one is a copy of `tsb_asm/tsb_asm.cppproj` in its own directory, with its
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name, its GUID, its source path and its `--section-start` changed (`0x7c00` for
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the 1 KiB tiers), plus four lines in the solution.
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`avrdevice` is a project property, so each project gets its own directory:
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Studio builds into `<project dir>/<Configuration>` whatever `OutputDirectory`
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says, and two projects sharing a directory would share one object file.
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## Debug keeps `-Os`
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Both configurations compile at `-Os`; Debug adds only `-gdwarf-4`. The `.text`
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is therefore identical in both, which is the point — a loader's section is a
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**correctness** bound and not a budget. `-Og` builds this same source to 590 B,
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and linking it at `--section-start=.text=0x7e00` on a 32 KiB part puts 78 bytes
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past flash end **without a diagnostic**: `rcall`/`rjmp` targets there wrap
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modulo flash size, so the image dies right after activation. A debug
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configuration that silently produces that is worse than none, and DWARF costs no
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flash, so the optimisation level stays where correctness needs it.
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## What Studio needs from the machine
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libavr from the **submodule**, found at
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`$(MSBuildProjectDirectory)\..\..\libavr\include` — correct by construction, and
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anchored to the project because a plain relative path resolves against the
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generated makefile's directory (the configuration's output directory), not the
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project's. There is no `LIBAVR_ROOT` escape hatch: a variable exported in a
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shell is invisible to Studio launched from the Start menu, and the failure reads
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as a missing `libavr/libavr.hpp` — which is what the submodule answers.
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A GCC 16.1 toolchain registered as flavour `avr-g++-16.1.0`, nothing older
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reaching `-std=c++26`.
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## Generating and gating
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One generated file is required before a project will load at all, and one command
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per project checks the flags have not drifted (both from libavr's
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`tools/atmelstudio/`):
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```sh
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for name in pureboot tsb_asm; do
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python libavr/tools/atmelstudio/componentinfo.py \
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"ide/$name/$name.componentinfo.xml" --device ATmega328P
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python libavr/tools/atmelstudio/check-flags.py \
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--solution ide/bootloader.atsln --project "$name" --target "$name" \
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--compile-commands build/atmega328p-generated/compile_commands.json \
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--log "build/as-$name.log"
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done
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```
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`--project` because one reference describes one binary; `--target` because
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`pureboot.cpp` is compiled by every point of the size matrix and the flags
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differ per point, so the basename alone does not name a reference. Release is
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what the gate compares — the presets define no debug build, and Debug differs
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from Release only in `-gdwarf-4`.
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Legacy (the yazoalfa-era submodules) stays on `master`.
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