FreeBSD on Firecracker

I never really realized that Firecracker VM is a full-blown machine and not just some sort of a Linux container tech. At first, it may sound like an ineffective approach, but if you take a closer look on a real-world usage example such as fly.io, you will be surprised: micro-VMs are very small and capable.

Once Colin's patches land on FreeBSD and Firecracker, the total boot time for the kernel is under 20ms. Absolutely incredible times that we live in.

Here&#x27;s the recent BSDCan talk from Colin that was posted a couple of days ago.<p><a href="https:&#x2F;&#x2F;youtu.be&#x2F;MT3cdeuRTzs?si=l6baNriUjcvy0ZOE" rel="nofollow noreferrer">https:&#x2F;&#x2F;youtu.be&#x2F;MT3cdeuRTzs?si=l6baNriUjcvy0ZOE</a>

qemu has microvm, inspired by firecracker<p><a href="https:&#x2F;&#x2F;qemu.readthedocs.io&#x2F;en&#x2F;latest&#x2F;system&#x2F;i386&#x2F;microvm.html" rel="nofollow noreferrer">https:&#x2F;&#x2F;qemu.readthedocs.io&#x2F;en&#x2F;latest&#x2F;system&#x2F;i386&#x2F;microvm.ht...</a>

It&#x27;s funny how many one second pauses turn out to be less than necessary. How many sysadmins took meaningful action because the system paused when they had an invalid machine uuid?

I&#x27;m not wanting to sound snoody. What use-cases do firecracker instances and the likes chime?<p>I use FreeBSD for everything from my colocated servers, to my own PC. By no means am I developer; seasoned Unix Admin at best. Bare-metal forever but welcome to the future. Especially anything that contributes to the OS.<p>However I hear buzz words like Lambda and Firecracker and really have no idea where the usage is. I get docker, containers, barely understand k8s but why do you need to spin up a VM only to tear it down compared to where you could just spin up a VM and use it when you really need to. Always there, always when.<p>Is it purely a cloud experience, cost saving exercise?

It&#x27;s a shame neither AWS nor macOS on ARM support nested virtualization. It would would make it far easier to develop and deploy Firecracker based tech.

Firecracker is amazing, but has a lot of edge cases that need documentation.<p>A huge thank you to Colin Percival for sharing this.<p>Particularly love the &quot;Once the low-hanging fruit was out of the way&quot; line... which to Colin means custom bus_dma patch(es).<p>Now anyone can now enjoy for free:<p>&quot;with 1 CPU and 128 MB of RAM, the FreeBSD kernel can boot in under 20 ms&quot;<p>If you&#x27;re used to devops with k8s clusters or lots of docker, this is absolutely amazing.

Toyed around with firecracker a bit. Does what it promises on boot times, but still a pretty gnarly experience. e.g. After doing a victory dance for getting it to boot I was rather deflated to find out that getting networking takes another lengthy tutorial

&gt; on a virtual machine with 1 CPU and 128 MB of RAM, the FreeBSD kernel can boot in under 20 ms;<p>Oh, my... how could I achieve the same on real hardware without VMs ? ;)

So firecracker vs v8 isolates if only doing js or wasm?