Auditing VRAM: Ensuring Every Gigabyte is Real

Counterfeit storage devices, such as USB flash drives and SSDs with modified controller firmware that report false capacities, rely on address wrapping: writes beyond physical memory silently overwrite earlier blocks modulo the actual capacity. With increased interest in home AI labs, one could imagine similar practices to start appearing in the second-hand GPU market. While … Continue reading Auditing VRAM: Ensuring Every Gigabyte is Real →

Acer Nitro V15 login hangs

When trying to enable the discrete NVIDIA GPU of the Acer Nitro ANV15-41[ANV], the graphical login screen "hangs": the OS works fine, but won't accept keyboard or touchpad input, which makes it unusable. It took me a day of wrong paths taken to realise that X11 picks the wrong input devices. The fix is to … Continue reading Acer Nitro V15 login hangs →

Trim on LUKS encrypted LVM root volumes

I noticed that fstrim wasn't working on my new Ubuntu 24.04 desktop installation, failing with "fstrim: /: the discard operation is not supported". In that setup, Ubuntu is installed into an LUKS encrypted LVM volume, so the ext4 file system, LVM and LUKS need to play nicely together for flash discard to work. That's how … Continue reading Trim on LUKS encrypted LVM root volumes →

Screen overlays in Linux

I heavily customise my Linux desktop setups, which includes binding scripts to hotkeys. Occasionally a visual feedback is useful (eg. when changing the CPU frequency). I'm aware of the following ways to display some sort of overlays which I tried with Ubuntu 24.04: Notifications Notify-send notifications display as simple rectangles. notify-send "Volume" "80%" Although there … Continue reading Screen overlays in Linux →

wpa_supplicant spam

Ubuntu 24.04 is spamming several of these entries in syslog: wpa_supplicant[1736]: wlp3s0: CTRL-EVENT-SIGNAL-CHANGE above=1 signal=-62 noise=9999 txrate=390000 The solution is to raise the wpa_supplicant logging level and restart networking: mkdir -p /etc/systemd/system/wpa_supplicant.service.d/ vi /etc/systemd/system/wpa_supplicant.service.d/log.conf # add these lines [Service] LogLevelMax=4 # save & quit systemctl daemon-reload systemctl restart wpa_supplicant.service systemctl restart NetworkManager.service