Category: Notes

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Yubikey GPG SSH Auth

GPG Agent for SSH Authentication (Update)

https://gist.github.com/mcattarinussi/834fc4b641ff4572018d0c665e5a94d3

echo "use-agent" >> ~/.gnupg/gpg.conf
echo "enable-ssh-support" >> ~/.gnupg/gpg-agent.conf
echo "IdentityAgent /run/user/1000/gnupg/S.gpg-agent.ssh" >> ~/.ssh/config

# Run the following to figure out what your SSH "A" key's Keygrip is:
gpg --list-keys --with-keygrip

# Add your key's keygrip to the sshcontrol file
echo A55719832AF939C531BACFFABB2A47B52FFBBF43 >> ~/.gnupg/sshcontrol

# Once you add the key to the sshcontrol file, you should see a key available to ssh-add
ssh-add -l
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Notes

Intel Processor Suffixes

From https://www.makeuseof.com/intel-u-vs-p-vs-h-laptop-cpus/, we have the following CPU suffixes/product-lines:

U-series

U means “ultra-low-power,” and that’s basically it—they’re chips that aren’t necessarily the very best in terms of CPU performance, but they’re instead low-power designs made with efficiency in mind. They have lower clock speeds, lesser cores, and more importantly, a very low TDP. The Intel Core i5-1265U is rated for 15W, and can turbo up to 55W in brief bursts. Some U chips go as low as 9W. These chips can be cooled relatively easily, and depending on the PC’s design, they could even be cooled passively.

https://www.makeuseof.com/intel-u-vs-p-vs-h-laptop-cpus

P-series

P chips sip a little more power—28W, to be precise. That’s almost twice (or even triple!) what a U-series chip requires. As such, power and thermal requirements for these chips are higher, and you’ll need beefier cooling. But at this point, it’s nothing that would make a thin and light laptop thicker than it should be, and with the right cooling, it shouldn’t be a problem.

https://www.makeuseof.com/intel-u-vs-p-vs-h-laptop-cpus

H-series

Unlike the P-line and U-line, the H-lineup is not made to fit into a thin, lightweight laptop. While those chips go up to 28W, an H CPU can go up to a whopping 45W. Granted, that’s not even close to a desktop CPU (the Core i9-12900K sips 125W), but for a laptop, that’s actually a lot—remember, they have enclosed, tightly-fitted spaces where internal components don’t have a lot of room to breathe. That doesn’t mean they’re not good. In fact, they’re pretty much as good as it gets for laptops.

https://www.makeuseof.com/intel-u-vs-p-vs-h-laptop-cpus

Intel’s description can be found https://www.intel.com/content/www/us/en/processors/processor-numbers.html

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Notes

QEMU/libvirt Setup

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Notes

MS Access

Notes for 32/64 bit usage and conversion:

Tools:

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Notes

QEMU Windows 11 Snapshots

You can’t take normal full featured libvirt snapshots, since we are using UEFI.

Although Chris makes a good point about not using external snapshots, I prefer to have the visual reminder in virt-manager that a snapshot is available. I’m going to give external snapshots a try anyways. Here are the relevant commands:

virsh snapshot-list $domain

# Create snapshot
virsh snapshot-create-as $domain --name $snapshotname --disk-only

# Check that we are now using the new snapshot qcow2 file
virsh domblklist $domain

# If we navigate to where the qcow2 files are stored, we
# should see the original img file and a new file
# Alternate path: /var/lib/libvirt/images
pushd ~/.local/share/libvirt/images
ls -al
# Running the file command can reveal the backing file info
file *

# To delete a snapshot metadata
virsh snapshot-delete --metadata $thedomain $snapshotname

# Also note ~/.config/libvirt directory
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QEMU Storage Performance

Comparing the emulated SATA and VirtIO, the VirtIO disk comes out massively faster.

Host machine is Debian on Intel Skylake with Samsung PM951 NVMe SSD.

It looks like IO speed might be CPU latency bound, since setting the virtual disk caching mode to unsafe doesn’t really improve the performance by much.

With the virtio disk caching set to “unsafe”, where it ignores guest sync requests.

Reference Performance of the underlying Samsung PM951 NVMe

https://www.samsung.com/us/labs/pdfs/collateral/sm951-prodoverview-0615-v1.pdf

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RDP on ChromeOS

The Microsoft Android RD client app seemed to be blocked fro install on certain Chromebooks, although it looks like this has been reversed. If it happens again, the next best RDP client is the Remmina, which can be installed through “Linux”/crostini.

# Statup Linux
sudo apt update
sudo apt install remmina
# Seacrh for remmina in ChromeOS search bar.