How to Compile Gem5 Linux Kernel? Easy Steps for Beginners!

Alright guys, today I’m gonna talk about how I compiled the Linux kernel for gem5. It wasn’t too difficult, but there were a few things that tripped me up along the way. So, I thought I’d share my experience to save you some trouble.

First things first, you need to have gem5 set up on your machine. Make sure you have the source code downloaded and ready to go. That’s step one, gotta have the simulator itself before we start messing with the kernel, right?

Now, the next thing is the build environment. gem5 uses something called SCons. I had to make sure I had the right version, which is 3.0 or greater. So, I spent some time figuring out my SCons situation. You gotta have all your ducks in a row before you start, am I right?

Then I realized, wait a minute, I need the actual Linux kernel source code. Duh! So, I grabbed that. Now, I’ve got gem5, SCons, and the Linux kernel source. We’re cooking with gas now!

Getting My Hands Dirty with the Kernel

Okay, so once I had all the pieces, I dove into the Linux kernel directory. I remember thinking, “This is it, no turning back now!” I started poking around and found the Makefile. This is where the magic happens, where you tell the system what you want to build.

Here’s a little trick I learned: don’t use make menuconfig every time you change something. I found out the hard way that it triggers a full recompilation, and let me tell you, that takes forever! Just use it when you need to, like when you’re setting things up for the first time.

• obj-m: This is for modules. I didn’t mess with this too much for this project, but it’s good to know what it is.
• all: This is the default target. If you just type make, this is what it’ll do.
• clean: This is your friend. Use it to clean up all the compiled files and start fresh. Trust me, you’ll need it.

I started with make defconfig, that gave me some settings. That got me a basic configuration, a good starting point. Then I started the compilation process with just make. Now, here’s a pro tip: use the -j option to speed things up. I set it to 4 to match my physical CPU cores, and it made a noticeable difference. It’s like having four people working on a project instead of one, you know?

After what felt like an eternity, but was probably just a few minutes, boom! The compilation finished. It felt great to see all those files get created. Like, “I did that!”

I was like a kid in a candy store. I had successfully compiled a Linux kernel for gem5. It was a good feeling. Hopefully, my little adventure here will help some of you out there. Don’t be afraid to experiment and try things out, that’s how you learn. And remember, make clean is your best friend when things go sideways!