Adding a SizeStudy directory

[rogurr]

The ./uefi/SizeStudy directory contains 2 drivers that both produce a hello world debug message string in the driver entry then exit, one written in C and the other in Rust. They are intended to be a baseline to allow making modifications such as adding C libraries or Rust Patina components to see how the changes affect size.

[Copilot]

Pull request overview

Adds a new uefi/SizeStudy area intended to serve as a baseline for measuring size impacts of simple UEFI “hello world” style drivers implemented in both C and Rust.

Changes:

• Introduces a minimal C DXE driver (CHelloWorld) that emits a DEBUG_INFO message and exits successfully.
• Introduces a Rust DXE driver (RustHelloWorld) with a PL011-UART-backed log implementation that emits an info! message and returns success.
• Adds documentation describing baseline size/compression comparisons and how to use the directory for experiments.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 8 comments.

Show a summary per file

File	Description
uefi/SizeStudy/RustHelloWorld/src/main.rs	New Rust DXE driver entrypoint with a simple UART logger and hello-world log message.
uefi/SizeStudy/RustHelloWorld/Cargo.toml	New Rust driver manifest defining dependencies and build profile settings.
uefi/SizeStudy/RustHelloWorld/.cargo/config.toml	New per-crate cargo configuration for aarch64-unknown-uefi build and linker flags.
uefi/SizeStudy/README.md	Documentation for the size study rationale and baseline measurement results.
uefi/SizeStudy/CHelloWorld/CHelloWorld.inf	New EDK2 INF for the C DXE driver baseline module.
uefi/SizeStudy/CHelloWorld/CHelloWorld.c	New C DXE driver baseline implementation emitting a debug message.

[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated no new comments.

Suppressed comments (2)

uefi/SizeStudy/CHelloWorld/CHelloWorld.c:6

• The C driver source header comment style (//// ...) doesn’t match the established UEFI C style in this repo, where sources start with a Doxygen-style /** @file header (e.g. uefi/SrePkg/Application/NvmeBpWrite/NvmeBpWrite.c:1). Aligning the header keeps documentation consistent and improves tooling support.

////
// SizeStudy baseline DXE driver that prints a debug message and exits, written in C.
//
// Copyright (c) Microsoft Corporation. All rights reserved.
// SPDX-License-Identifier: MIT

uefi/SizeStudy/RustHelloWorld/Cargo.toml:16

• log is used from a #![no_std] UEFI binary, but this dependency enables default features. In this repo’s UEFI Rust crates, log is consistently pulled in with default-features = false (e.g. uefi/crates/patina_boot/Cargo.toml, uefi/OdpPkg/Drivers/ODP_PatinaSmbiosDemo/Cargo.toml), which also helps keep the size-study baseline smaller and avoids accidentally relying on std.

  log = { version = "0.4" }

[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated no new comments.

Suppressed comments (1)

uefi/SizeStudy/RustHelloWorld/Cargo.toml:17

• log is pulled in with default features enabled. For a #![no_std] UEFI driver (and especially for a size baseline), this can unnecessarily pull in std support from log and inflate the resulting .efi size. Other UEFI crates in this repo consistently disable log default features.

[dependencies]
  arm-pl011-uart = { version = "0.5.0", default-features = false }
  log = { version = "0.4" }
  spin = { version = "0.10.0", default-features = false, features = ["mutex", "spin_mutex"] }