How to Build a Mendel Linux Error for Coral Dev Board

If you’ve ever tried to build Mendel Linux for the Google Coral Dev Board on a system like Ubuntu 20.04, you probably know the feeling: you follow the instructions exactly, run the build, wait patiently… and then nothing. No u-boot.imx. No rootfs_arm64.img. Just a bunch of logs, some warnings, and no clear output.

I’ve been there and I want to share how I troubleshooted the problem, fixed it, and improved the whole process. If you’re stuck at the same point, this guide is for you.

Initial Build Setup

I followed the official Coral Getting Started instructions. Here’s a breakdown of the commands I ran:

# Step 1: Clone the Mendel build environment
repo init -u https://coral.googlesource.com/manifest -b mendel-linux

# Step 2: Sync all repositories
repo sync

# Step 3: Source the build environment
source build/envsetup.sh

# Step 4: Choose your target device
lunch mendel-imx8m_phanbell-userdebug

# Step 5: Start the build
m

At first, everything seemed fine no crashing, no red flags. But at the end? No boot images. No u-boot.imx, no rootfs_arm64.img.

The Error That Tripped Me Up

When I dug into the logs, this message jumped out:

ERROR: ld.so: object 'libfakeroot-sysv.so' from LD_PRELOAD cannot be preloaded (cannot open shared object file): ignored.

That doesn’t seem fatal at first glance and maybe it wasn’t the fatal error but it did point to a broken toolchain, and ultimately a broken build.

Define Error

Here’s what I learned:

fakeroot is a tool that helps simulate file ownership and permissions, especially when building as a non-root user.
It works by preloading a shared library like libfakeroot-sysv.so to fake root capabilities.
This error means the dynamic linker couldn’t find or load that library even though it was supposed to.

And that’s a problem when you’re building in a chrooted or isolated environment, such as pbuilder.

I even tried creating a symbolic link like this:

ln -s /usr/lib/x86_64-linux-gnu/libfakeroot/libfakeroot-sysv.so /usr/lib/libfakeroot-sysv.so

But that didn’t help because the build environment couldn’t see it anyway.

How I Fix It

Install fakeroot Inside the Chroot

If you’re using something like pbuilder, the host fakeroot doesn’t matter you need it inside the isolated environment.

Here’s what I did:

sudo pbuilder login --save-after-login
# Now you're inside the pbuilder shell:
apt-get update
apt-get install fakeroot
exit

Then I rebuilt:

Boom much smoother build process.

Ensure LD_PRELOAD Path is Correct

On my host system (Ubuntu 20.04), the correct library path was:

export LD_PRELOAD=/usr/lib/libfakeroot/libfakeroot-sysv.so

Double-check it with:

ls -l /usr/lib/libfakeroot/libfakeroot-sysv.so

If it’s missing or corrupted, reinstall:

sudo apt-get install --reinstall fakeroot

Extra Improvement I Made to My Build Process

Once everything started working, I didn’t stop there. I wanted to make my setup reliable, repeatable, and fast.

Automated Setup with a Shell Script

I wrote a simple script to bootstrap my builds:

#!/bin/bash

set -e  # Stop if anything fails

echo "[INFO] Setting up build environment..."
source build/envsetup.sh
lunch mendel-imx8m_phanbell-userdebug

echo "[INFO] Starting build..."
m -j$(nproc)

echo "[INFO] Build complete."

I saved it as build_mendel.sh and made it executable:

chmod +x build_mendel.sh
./build_mendel.sh

Manual Output Check

Sometimes, the build finishes, but you’re still not sure what was produced. I added a post-check step to look for expected files:

cd out/target/product/imx8m_phanbell/

if [ ! -f "u-boot.imx" ]; then
    echo "[ERROR] u-boot.imx not found!"
    exit 1
fi

if [ ! -f "rootfs_arm64.img" ]; then
    echo "[ERROR] rootfs_arm64.img not found!"
    exit 1
fi

echo "[SUCCESS] All required images are built."

Speeding Thing Up with ccache

Rebuilding from scratch was taking forever. I installed ccache and enabled it:

sudo apt install ccache
export USE_CCACHE=1
export CCACHE_DIR=~/.ccache

Now repeated builds are noticeably faster.

Final Thought

This whole process taught me something important even if a build doesn’t crash, it doesn’t mean it succeeded.

It seemed harmless at first. But it was a symptom of a deeper issue and once I addressed it by making sure fakeroot was installed inside the build environment, everything started clicking into place.