Broadcom BCM4360 WiFi fix for CachyOS Live ISO

BCM4360FixForCachyOsLiveIso.md

Fixing Broadcom BCM4360 WiFi on CachyOS Live ISO

This guide explains how to patch the official CachyOS Live ISO build system to make WiFi work out-of-the-box on older Apple devices using the infamous Broadcom BCM4360 chipset.

Tested on:

• MacBook Air 2013
• Broadcom BCM4360
• CachyOS Desktop ISO

The Problem

The default CachyOS live environment does not detect WiFi networks on some Apple laptops using Broadcom chipsets.

The issue is caused by conflicting kernel modules being loaded before the proprietary wl driver.

Typical symptoms:

• No WiFi networks detected
• No wireless interface appears
• ip link only shows lo
• modprobe wl fails
• Installer cannot continue because there is no network connection

Root Cause

The Linux kernel automatically loads open-source Broadcom drivers such as:

• b43
• b43legacy
• bcma
• brcmsmac
• ssb

These conflict with the proprietary Broadcom driver required by BCM4360 devices.

The solution is:

1. Install broadcom-wl-dkms
2. Prevent conflicting modules from loading
3. Force the wl module to load early during boot

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Prerequisites

Make sure to have another working CachyOS system with access to terminal. Do not try to do this from the broken MacBook live ISO itself or from another CachyOS live.

You need:

• Another physical machine running CachyOS
• OR a virtual machine running CachyOS

The reason is simple:

• The original live ISO has no working WiFi on BCM4360 devices
• You cannot download packages or rebuild the ISO from the affected machine
• The ISO must be patched and rebuilt elsewhere first

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Step 1: Setup CachyOS Live ISO repository

sudo pacman -Syy
sudo pacman -S archiso mkinitcpio-archiso git squashfs-tools grub --needed
git clone https://github.com/cachyos/cachyos-live-iso.git cachyos-archiso
cd cachyos-archiso

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Step 2: Modify package list

Edit:

archiso/packages_desktop.x86_64

Add:

broadcom-wl-dkms
dkms
linux-cachyos-headers

Remove:

b43-fwcutter

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Step 3: Blacklist conflicting Broadcom modules

Edit:

archiso/airootfs/etc/modprobe.d/broadcom-wl.conf

Add these lines:

blacklist b43
blacklist b43legacy
blacklist bcma
blacklist brcmsmac
blacklist ssb

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Step 4: Force wl module loading

Create:

archiso/airootfs/etc/modules-load.d/wl.conf

Contents:

wl

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Step 5: Build the ISO

sudo ./buildiso.sh -p desktop -v -w

Wait for the build to complete successfully, this should take 30-40 minutes.

Do not interrupt the process.

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Step 6: Boot the patched ISO

Write the ISO to USB or use Ventoy.

After booting:

• WiFi networks should appear immediately
• NetworkManager should detect the wireless adapter automatically
• The installer should work normally

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Notes

• This fix is specifically intended for BCM4360-based Apple laptops
• It may not be appropriate for all Broadcom devices
• The aggressive blacklist is intentional
• This was tested on a MacBook Air 2013

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Useful Debug Commands

lsmod | grep wl

modinfo wl

lspci -k | grep -A 5 -i network

lsmod | grep -E 'wl|b43|bcma|brcmsmac|ssb'

ip link

rfkill list

sudo dmesg | grep -i broadcom

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Why DKMS Instead of broadcom-wl?

Using broadcom-wl-dkms ensures compatibility with the CachyOS kernel shipped inside the live ISO.

The standard broadcom-wl package may not always match the exact kernel version used during ISO generation.

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Final Result

After applying this patch:

• The live ISO detects WiFi correctly
• The CachyOS installer works normally
• BCM4360 Apple devices become fully usable without external adapters or tethering