Understanding QEMU Devices (2018)

QEMU along with Bochs were my first tries getting into virtualization &#x2F; emulation way back (maybe around early 2000s? I can&#x27;t remember!).<p>Although the emulation &#x2F; virtualization market already grew larger with more and more options available today, QEMU was (and still is) one of the most awesome projects out there.

If you’re on a Mac, UTM is an excellent wrapper around Qemu.<p><a href="https:&#x2F;&#x2F;mac.getutm.app&#x2F;" rel="nofollow">https:&#x2F;&#x2F;mac.getutm.app&#x2F;</a>

What is the definitive new-comer friendly guide to QEMU? Not just about using it but also understanding its internals (say to add new instructions to a supported ISA etc)?

&gt; so the QEMU developers have added the virtio-net card (a PCI hardware specification, although no bare-metal hardware exists yet that actually implements it)<p>Things have changed since 2018. BlueField DPUs provide virtio network [1] and block [2] devices in the host PCI space. These can be passed through to VMs using vfio-pci in the host.<p>1. <a href="https:&#x2F;&#x2F;docs.nvidia.com&#x2F;networking&#x2F;display&#x2F;bluefieldvirtionetv190&#x2F;Virtio-net+Deployment" rel="nofollow">https:&#x2F;&#x2F;docs.nvidia.com&#x2F;networking&#x2F;display&#x2F;bluefieldvirtione...</a><p>2. <a href="https:&#x2F;&#x2F;docs.nvidia.com&#x2F;networking&#x2F;display&#x2F;bluefield2snap380" rel="nofollow">https:&#x2F;&#x2F;docs.nvidia.com&#x2F;networking&#x2F;display&#x2F;bluefield2snap380</a><p>Disclaimer: I work for NVIDIA, have used BlueField DPUs, but have not used the virtio feature.

QEMU is a great piece of software. I use it regularly to debug various cross compiled kernel images under gdb without requiring actual ARM hardware (buildroot + custom kernel + gdb).

qemu is a treasure and reading its source to learn how computers work is very fun.

&gt; Understanding QEMU...<p>Best of luck

&quot;USB disk as &#x2F;dev&#x2F;sda on a not-rooted smartphone using Termux, QEMU, Alpine Linux&quot;: <a href="https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=40507319">https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=40507319</a>

This is such a fantastic description of what is going on underneath the hood - it took me quite a while to understand how qemu works, wish I had seen this before!

&gt; QEMU actually has the ability to glue together a lot of different host formats (raw, qcow2, qed, vhdx, …)<p>&gt; and protocols (file system, block device, NBD, Ceph, gluster, …)<p>Yeah, and it&#x27;s awesome. With qcow2 images mounted via nbd, I was able to manipulate ddrescue images without modifying the original. Truly one of the most useful software ever written. I even use it on Android with Termux to use and test x86_64 software.<p>I wish there was a step by step porting and implementation guide. I tried to port the open source Sensor Watch board to QEMU in order to facillitate software development for it. Didn&#x27;t get very far. I&#x27;m not particularly knowledgeable about electronics but I had all the hardware documentation, I feel like it should have been enough.

Warning for humans! If you are trying to run a virtual PC on QEMY let&#x27;s say on bare metal hosting from hetzner, you will very soon discover - QEMU is a dead slow without actual graphic card or at best you will get all kind of funky missing libs error messages on Ubuntu and other OS in very surprise spots.<p>Had a very good experience simulating K8s cluster with QEMU aka studing K8s hard way once I figure out how networking actually works between virtual machines and domains can be assigned with external proxy.