# Syzkaller Build Loop

> Full build workflow for adding new syscall descriptions to syzkaller Use when this capability is needed.

- Skill: `tomevault-io/syzkaller-build-loop` (Agent Skill, multi-file: 2 files)
- Install (CLI): `npx skillmds@latest add tomevault-io/syzkaller-build-loop`
- Raw SKILL.md: https://api.skillmd.com/api/skills/tomevault-io/syzkaller-build-loop/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Productivity
- Author: tomevault-io (https://skillmd.com/u/tomevault-io)
- Updated: 2026-09-17
- Page: https://skillmd.com/skills/tomevault-io/syzkaller-build-loop

---


# Syzkaller Description Workflow

## Full Build Loop for New Descriptions

When adding new syscall descriptions, follow this workflow:

```bash
cd /opt/syzkaller

# 1. Write/edit your .txt file in sys/linux/

# 2. Create a .const file with constant values (see syz-extract-constants skill)
#    The .const file should be named: sys/linux/your_file.txt.const

# 3. Compile descriptions
make descriptions

# 4. Build syzkaller
make all
```

## Quick Rebuild (After Minor Edits)

If you only changed descriptions (not constants):

```bash
cd /opt/syzkaller
make descriptions   # Runs syz-sysgen to compile descriptions
```

If you add new constants, update the `.const` file first.

## Common Errors

### Unknown type
```
unknown type foo_bar
```
- Type not defined, or defined after first use
- Define all types before using them

### Constant not available / defined for none of the arches
```
SOME_CONST is defined for none of the arches
```
- The constant isn't in the `.const` file
- Add it to `sys/linux/your_file.txt.const` with the correct value

### Missing reference
```
undefined reference to 'some_type'
```
- Type defined in another file not being found
- Check includes or existing type definitions

## Exploring Existing Code

Find examples of patterns:
```bash
grep -r "pattern" /opt/syzkaller/sys/linux/
```

Useful searches:
- `resource fd_` - How other fd resources are defined
- `ioctl\$` - Ioctl definition patterns
- `read\$` / `write\$` - Read/write specializations
- `struct.*{` - Struct definition patterns

## Files to Reference

- `sys/linux/socket.txt` - Network types (ifreq_t, sockaddr, etc.)
- `sys/linux/sys.txt` - Basic syscall patterns
- `sys/linux/fs.txt` - File operations

---
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<!-- tomevault:4.0:skill_md:2026-04-11 -->