fix(esp32c3): use semihosting _exit for QEMU emulator support

[luoliwoshang]

Summary

Remove conflicting _exit implementations to enable semihosting support for ESP32-C3 QEMU emulator.

Background

Previously, multiple _exit implementations existed in newlib:

• libnosys/_exit.c - stub implementation
• libgloss/riscv/sys_exit.c - another stub
• syscalls.c - uses asm("unimp") which crashes in QEMU
• semihost-sys_exit.c - proper semihosting implementation using ebreak

The syscalls.c version was being linked, causing QEMU to crash with "Illegal instruction".

Solution

After goplus/newlib#10 separates _exit from syscalls.c, we can simply remove the other stub implementations (libnosys/_exit.c and libgloss/riscv/sys_exit.c). This leaves semihost-sys_exit.c as the only _exit implementation, which will be automatically used from the existing .a library.

Changes

Remove conflicting _exit implementations from compile list:

• libnosys/_exit.c
• libgloss/riscv/sys_exit.c (3 occurrences in different compile groups)

Result

Now ESP32-C3 programs properly use semihosting _exit and exit cleanly in QEMU with -semihosting flag.

Depends on

• refactor(esp): split _exit into separate file for QEMU support newlib#10 (splits _exit from syscalls.c to syscalls_exit.c)

Test plan

• Build ESP32-C3 target
• Run in QEMU emulator with -semihosting flag
• Verify program exits cleanly using semihosting

🤖 Generated with Claude Code

[gemini-code-assist]

Summary of Changes

Hello @luoliwoshang, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request addresses an issue where the ESP32-C3 QEMU emulator was not correctly utilizing the semihosting _exit function due to conflicting implementations. By strategically commenting out redundant _exit definitions within the build configuration, this change ensures that the intended semihosting _exit is consistently invoked, leading to proper program termination in the QEMU environment.

Highlights

• Conflicting _exit implementations resolved: This PR resolves conflicts among multiple _exit implementations by commenting out libnosys/_exit.c and libgloss/riscv/sys_exit.c from the build process. This ensures that the correct semihosting _exit is used for ESP32-C3 QEMU emulation.
• Improved ESP32-C3 QEMU support: By ensuring the semihosting _exit is used, ESP32-C3 programs now properly terminate in the QEMU emulator with an expected ebreak instruction, leading to clean exits.

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[gemini-code-assist]

Code Review

This pull request correctly addresses the conflicting _exit symbol implementations for ESP32-C3 QEMU support by commenting out the stub versions from the build configuration. The changes are logical and well-explained in the description. I've added one comment regarding code duplication in the file list, which could be addressed to improve maintainability.

[xgopilot]

Code Review Summary

The PR correctly addresses the immediate issue of conflicting _exit implementations for ESP32-C3 QEMU semihosting support. However, the review identified critical pre-existing code quality issues that should be addressed:

Critical Issues Found:

• Massive code duplication: 33 files duplicated at lines 262-294, plus 11 files appearing a third time at lines 296-306
• Missing inline documentation: Commented-out lines lack explanatory comments for future maintainers

Recommendation:

• ✅ This PR can be merged to fix the immediate semihosting conflict
• ⚠️ Follow-up PR needed to remove duplicated file entries and add documentation

See inline comments for specific details.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.01%. Comparing base (f6337d4) to head (c45489f).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1539      +/-   ##
==========================================
- Coverage   91.01%   91.01%   -0.01%     
==========================================
  Files          45       45              
  Lines       11971    11966       -5     
==========================================
- Hits        10896    10891       -5     
  Misses        899      899              
  Partials      176      176              

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[luoliwoshang]

it's reduant file,actually we not connect symbol from these files.

[luoliwoshang]

@xgopilot it's a not a expect diff , make it have not diff of main branch!

[xgopilot]

Fixed Whitespace Issue ✓

Changes completed:

• Read comment history to understand the issue
• Compare current branch with main branch
• Identify unexpected differences
• Fix the whitespace issue in esp32-riscv.app.elf.ld
• Commit changes locally

What I Fixed

The targets/esp32-riscv.app.elf.ld file had an unintended whitespace change on line 25:

• Before: .rodata : (4 spaces)
• After: .rodata : (1 space)

This formatting change was unrelated to the PR's purpose (semihosting _exit support). I've reverted it, and the file now matches the main branch exactly.

Permission Required

Hi @luoliwoshang! I've prepared your changes locally but need permission to push to your fork.

View Details & Solution

Target: luoliwoshang/llgo (fork)

Push blocked:

remote: Invalid username or token. Password authentication is not supported for Git operations.
fatal: Authentication failed for 'https://github.com/luoliwoshang/llgo.git/'

---

Alternative: Manual Push

Since you own the fork, you can pull and push the changes yourself:

# Fetch the changes from the main repo
git fetch origin

# Cherry-pick my commit
git cherry-pick b3ee8066

# Or apply the simple fix directly
# In targets/esp32-riscv.app.elf.ld line 25, change:
#   .rodata :
# To:
#   .rodata    :
# (add 3 more spaces after .rodata)

# Then push
git push origin esp32c3/exitsemi

[luoliwoshang]

@xgopilot now you can create the fork pr to me ! just do it!

[xgopilot]

Fork PR Created Successfully ✓

• Check current branch and changes
• Fix whitespace issue in esp32-riscv.app.elf.ld
• Commit and push changes to fork
• Create PR back to your repository

What I Did

I've successfully created a fork PR back to your repository! Here's what was completed:

1. Fixed the whitespace issue in targets/esp32-riscv.app.elf.ld line 25:

   • Changed .rodata : (1 space) → .rodata : (4 spaces)
   • This matches the formatting in the main branch

2. Committed the change with proper attribution

3. Pushed to your fork at luoliwoshang/llgo

4. Created PR sqlite demo #182: fix(esp32c3): restore whitespace in linker script to match main

   • Source: fork-pr-1539-1768440281
   • Target: esp32c3/exitsemi

Next Steps

You can now review and merge PR #182 in your fork repository to incorporate this whitespace fix into your esp32c3/exitsemi branch.