Driving a 4-pin computer PWM fan on the BTT Octopus using Klipper

Regular fans for 3D printers have just two wires, power and ground, and we vary the average supply voltage to the fan using PWM to change its speed.

However 4-wire computer fans like Noctuas are different, these fans expect a steady 12V power supply and a separate 5V PWM signal to set their speed. Check the pinout of your fan’s connector here:

https://noctua.at/en/what-pin-configuration-do-noctua-products-use

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Expanding the disk of your Proxmox macOS VM

Have you run out of room on your macOS VM’s disk? Here’s how you can expand it.

In the Hardware tab for your VM, select your disk and click the “resize disk” button at the top of the page. Enter the size increment in gigabytes (note, this is not the final size you want to achieve, it is the amount the disk will grow by).

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Installing macOS 12 “Monterey” on Proxmox 7

This tutorial for installing macOS 12 Monterey has been adapted for Proxmox from Kholia’s OSX-KVM project and Leoyzen’s OpenCore configuration for KVM. You can get the full sourcecode of my OpenCore release on my GitHub here.

Requirements

I’ll assume you already have Proxmox 7 installed. You also need a real Mac available in order to fetch the OSK key.

Your Proxmox host computer’s CPU must support SSE 4.2, so for Intel your CPU must be at least as new as Nehalem, which was the first CPU generation to bear the “Core” i5/i7 branding. Older CPUs will cause Illegal Instruction crashes when apps/extensions attempt to use these missing instructions.

Modern AMD CPUs also support SSE 4.2 and will work with this guide.

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Recovering lost GPG public keys from your YubiKey

Have you ever generated GPG keys, loaded them into your YubiKey, and then thrown away/erased your computer? You’ll discover that when you take your YubiKey to a new computer, GPG refuses to automatically import your key when running --card-status.

The common wisdom on the Internet is that this is because YubiKeys (and Smart Cards in general) don’t store your public keys at all, they only store your private keys, so you must import your public keys from a backup or a public keyserver instead. If you don’t have such a backup, you’re screwed.

However, I investigated this and found that this common wisdom wasn’t true. I was able to recover my public keys from my YubiKey 4 even on a brand new, erased computer. Here’s how you can, too.

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Installing macOS 12 “Monterey” Developer Beta on Proxmox 6

With the public release of Monterey, this guide is now obsolete, please use my new installation guide instead

This tutorial for installing macOS Monterey Developer Beta has been adapted for Proxmox from Kholia’s OSX-KVM project and Leoyzen’s OpenCore configuration for KVM. You can get the full sourcecode of my OpenCore release on my GitHub here.

Requirements

Since Monterey is still in closed Developer Beta, you need to be an Apple Developer and have access to a Mac (or Mac VM) to download it.

Your Proxmox host computer’s CPU must support SSE 4.2, so for Intel your CPU must be at least as new as Nehalem, which was the first CPU generation to bear the “Core” i5/i7 branding. Older CPUs will cause Illegal Instruction crashes when apps/extensions attempt to use these missing instructions.

Modern AMD CPUs also support SSE 4.2 and will work with this guide.

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Magic Trackpad 2 causes kernel heap corruption when passed to a Proxmox guest, GPFs

In mid-December I rebooted to upgrade my Proxmox kernel to pve-kernel-5.4.78-2-pve, but I immediately started having an issue where the kernel would trigger a GPF (general protection fault) and reset about 5-20 minutes after starting my macOS VM. I suspected that the new kernel was at fault, but I rolled back to the previous kernel and the problem persisted. I hadn’t experienced this fault before so I was a bit baffled about what change I made before that reboot could have triggered it.

To track down the issue, I built a version of Proxmox’s kernel with KASAN enabled. KASAN is the Kernel Address Sanitiser, it can detect kernel bugs like double-frees or out-of-bounds reads and writes by instrumenting the kernel to add checks around every memory access. This adds a bunch of CPU and memory space overhead, but the impact is bearable so long as your guest doesn’t need much service from the host kernel.

Continue reading Magic Trackpad 2 causes kernel heap corruption when passed to a Proxmox guest, GPFs

Running Tails as a VM with persistence on Proxmox

In this guide I’ll explain how you can run Tails as a VM in Proxmox while retaining the persistence feature, and keeping support for Proxmox backups and snapshots.

Firstly, note that running Tails as a VM defeats a lot of the security features it offers, since you now need to trust the hypervisor to be secure. The VM’s memory could be swapped to disk in the host’s swapfile or persisted in a guest snapshot (if the “include RAM” option is ticked), which will leak the contents of the guest onto the host’s persistent storage, including secret encryption key material.

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Working around the AMD GPU Reset bug on Proxmox using vendor-reset

Most modern AMD GPUs suffer from the AMD Reset Bug: The card cannot be reset properly, so it can only be used once per host power-on. The second time the card is tried to be used Linux will attempt to reset it and fail, causing the VM launch to fail, or the guest, host or both to hang.

gnif’s new vendor-reset project is an attempt to work around this AMD reset issue by replacing AMD’s missing FLR support with vendor-specific reset quirks.

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Solving macOS VM kernel panics on heavily-loaded Proxmox/QEMU/KVM servers

Recently I needed to solve a problem where macOS VMs running on an overloaded Proxmox server (regularly pegged at 100% CPU, load >100) would kernel-panic and reboot about once every 15 minutes. All of the VMs on the box were running a CI workload, so Proxmox was effectively running a CPU torture-test similar to building Chrome in a loop. However, only the macOS guests were experiencing kernel panics.

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Installing macOS 11 “Big Sur” on Proxmox 6

macOS 12 Monterey is now available! If you want to install that instead, check out my newer guide!

This tutorial for installing macOS Big Sur using OpenCore has been adapted for Proxmox from Kholia’s OSX-KVM project and Leoyzen’s OpenCore configuration for KVM. You can get the full sourcecode on my GitHub here.

Requirements

I’ll assume you already have Proxmox 6 installed. You also need a real Mac available in order to fetch the OSK key.

Your Proxmox host computer’s CPU must support SSE 4.2, so for Intel your CPU must be at least as new as Nehalem, which was the first CPU generation to bear the “Core” i5/i7 branding. Older CPUs will cause the finder to repeatedly crash after installation completes (with an Illegal Instruction exception in the graphics code).

Modern AMD CPUs also support SSE 4.2 and will work with this guide.

Continue reading Installing macOS 11 “Big Sur” on Proxmox 6