Arno's questions

After return from suspend the screen of my laptop flickers. You can't continue work with that. In kernel log you see :

[drm:intel_cpu_fifo_underrun_irq_handler [i915]] *ERROR* CPU pipe A FIFO underrun

So I played with display settings. Changing the refresh rate doesn't help, but lower the resolution (from 1920x1080). So in any lower resolution I don't have a problem. But of course I have to loose a lot of pixels when using a default resolution. So I decided to add my own 1912x1080. For some strange reason this is enough to avoid flickering.

So I added this lines to my ~./profile:

xrandr --newmode "1912x1080_60.00"  171.25  1912 2032 2232 2552  1080 1083 1093 1120 -hsync +vsync
xrandr --addmode eDP-1 "1912x1080_60.00"

and select this resolution. The issue is gone but I am really wondering what is root cause of this?

My system is a Skylake core-m5-6Y54 system, running Ubuntu Mate 20.04.

Does someone is able to convert the caja meld plugin to become compatible with Ubuntu Mate 20.04? That is a very important plugin for me, beside the open as admin .....

An old one is here: http://www.giuspen.com/software/cajapyext/meld-compare.py

Thanks a million.

I need scale my screen to read 1920x1080 resolution at a 12" screen. For this I found this line is great:

xrandr --output eDP-1 --scale 0.9x0.9

How can I include that while the original setup of screen, so as early as possible? Any X11 config file? Where and how?

Thank you!

My problem with adding it later is that screen (intel skylake) starts flickering after suspend or reconfiguring. I filed that bug (https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1872760) but have not much hope for a quick solution of that.

My laptop shows in powertop (idle tab) GPU power on 100%. RC6 or other energy saving states 0%. I check my old laptop - it was different there. Reading about it I found the parameter enable_rc6. It was "1" at my old laptop - but not at all available with my new one. (Core m5 Skylake, Ubuntu 18.04 Mate - old laptop same Ubuntu but N3530).

Edit:
(I repeated test installing Linux Mint Mate 19.03 - also an Ubuntu kernel - With initial Kernel 5.0 it was working. Rc6 was used most of the time. After the update to Kernel 5.3, this disappeared. So it seems to be a regression of the new Kernel).

:~$ modinfo -p i915
modeset:Use kernel modesetting [KMS] (0=disable, 1=on, -1=force vga console preference [default]) (int)
enable_dc:Enable power-saving display C-states. (-1=auto [default]; 0=disable; 1=up to DC5; 2=up to DC6) (int)
enable_fbc:Enable frame buffer compression for power savings (default: -1 (use per-chip default)) (int)
lvds_channel_mode:Specify LVDS channel mode (0=probe BIOS [default], 1=single-channel, 2=dual-channel) (int)
panel_use_ssc:Use Spread Spectrum Clock with panels [LVDS/eDP] (default: auto from VBT) (int)
vbt_sdvo_panel_type:Override/Ignore selection of SDVO panel mode in the VBT (-2=ignore, -1=auto [default], index in VBT BIOS table) (int)
reset:Attempt GPU resets (0=disabled, 1=full gpu reset, 2=engine reset [default]) (int)
vbt_firmware:Load VBT from specified file under /lib/firmware (charp)
error_capture:Record the GPU state following a hang. This information in /sys/class/drm/card<N>/error is vital for triaging and debugging hangs. (bool)
enable_hangcheck:Periodically check GPU activity for detecting hangs. WARNING: Disabling this can cause system wide hangs. (default: true) (bool)
enable_psr:Enable PSR (0=disabled, 1=enabled) Default: -1 (use per-chip default) (int)
force_probe:Force probe the driver for specified devices. See CONFIG_DRM_I915_FORCE_PROBE for details. (charp)
alpha_support:Deprecated. See i915.force_probe. (bool)
disable_power_well:Disable display power wells when possible (-1=auto [default], 0=power wells always on, 1=power wells disabled when possible) (int)
enable_ips:Enable IPS (default: true) (int)
fastboot:Try to skip unnecessary mode sets at boot time (0=disabled, 1=enabled) Default: -1 (use per-chip default) (int)
prefault_disable:Disable page prefaulting for pread/pwrite/reloc (default:false). For developers only. (bool)
load_detect_test:Force-enable the VGA load detect code for testing (default:false). For developers only. (bool)
force_reset_modeset_test:Force a modeset during gpu reset for testing (default:false). For developers only. (bool)
invert_brightness:Invert backlight brightness (-1 force normal, 0 machine defaults, 1 force inversion), please report PCI device ID, subsystem vendor and subsystem device ID to [email protected], if your machine needs it. It will then be included in an upcoming module version. (int)
disable_display:Disable display (default: false) (bool)
mmio_debug:Enable the MMIO debug code for the first N failures (default: off). This may negatively affect performance. (int)
verbose_state_checks:Enable verbose logs (ie. WARN_ON()) in case of unexpected hw state conditions. (bool)
nuclear_pageflip:Force enable atomic functionality on platforms that don't have full support yet. (bool)
edp_vswing:Ignore/Override vswing pre-emph table selection from VBT (0=use value from vbt [default], 1=low power swing(200mV),2=default swing(400mV)) (int)
enable_guc:Enable GuC load for GuC submission and/or HuC load. Required functionality can be selected using bitmask values. (-1=auto, 0=disable [default], 1=GuC submission, 2=HuC load) (int)
guc_log_level:GuC firmware logging level. Requires GuC to be loaded. (-1=auto [default], 0=disable, 1..4=enable with verbosity min..max) (int)
guc_firmware_path:GuC firmware path to use instead of the default one (charp)
huc_firmware_path:HuC firmware path to use instead of the default one (charp)
dmc_firmware_path:DMC firmware path to use instead of the default one (charp)
enable_dp_mst:Enable multi-stream transport (MST) for new DisplayPort sinks. (default: true) (bool)
enable_dpcd_backlight:Enable support for DPCD backlight control (default:false) (bool)
enable_gvt:Enable support for Intel GVT-g graphics virtualization host support(default:false) (bool)

I added powertop to /etc/sudoers (sudo visudo) but it doesn't work. I checked all possible problems I can imagine. What did I missed?

user@ellie:~$ whoami
user
user@ellie:~$ groups
user adm cdrom sudo dip plugdev lpadmin sambashare
user@ellie:~$ ll /etc/sudoers
-r--r----- 1 root root 1093 Feb  6 19:05 /etc/sudoers

user@ellie:~$ sudo powertop
[sudo] Passwort für user: 
user@ellie:~$ sudo cat /etc/sudoers | grep powertop
[sudo] Passwort für user: 
ALL ALL=(ALL:ALL) NOPASSWD: /usr/sbin/powertop
user@ellie:~$ which powertop
/usr/sbin/powertop
user@ellie:~$ BB

I am in group sudo, permissions seem to be ok, path to powertop checked. But you see, if I type in "sudo powertop" it ask for a password ?!? (In my first attempt the first "ALL" was just "user")

I would like to add this command "systemctl suspend-then-hibernate" to a key-combination (ALT+s). For some unknow reason it ask for permission, but it doesn't ask for "systemctl hibernate" or "systemctl suspend". What might be the reason? I also checked sudoers. Adding this doesn't help. I am not sure how this commands operate - don't find anything in the /etc path. Can someone give me a hint? In best case I would replace "suspend" by this "suspend-then-hibernate" also in powermanager, e.q. for close-lid. Thank you (Running ubuntu mate 18.04)

Have a Linux PC and an ARM-board. Want to boot the ARM-board into a rootfs hosted on the PC (cross/remote)

I export a rootfs in my home, so /etc/exports looks like:

/home/user/rootfs 172.20.20.0/24(anonuid=0,anongid=0,async,rw,no_subtree_check)

Now I want that a certain folder (lets assume /home/user/example/opt) is linked to /home/user/rootfs/opt. That works fine via a mount bind. So at PC I can navigate through directories and see that files in /home/user/rootfs/opt BUT: The device that boots into that NFS doesn't see this /opt folder (or the content in it).

Do I have a chance to solve that? Maybe I need a different approach or have to add a line in /etc/exports fo my PC?

BT is enabled at startup. This is nice. But it will not autopair/connect to a device, even if it is once paired and get status "trusted". I can connect to a Speaker with the tool by selecting device, and "connect to audio output". How can this done automatically on boot? I can do this also with "bluetoothctl" and than "connect ", but this is interactive, seems not scriptable.

And second step is, that BT becomes default audio sink.
Isn't that all an ordinary use case?

(I found some pages here, most are outdated.) Autoconnecting Bluetooth Devices: load-module module-switch-on-connect doesn't work for me.

I also installed bt-autoconnect. But several issues: - it didn't foun the BT-Adapter - Button Audio-Setting does just nothing - Save and quit doesn't just nothing

I have a few problems with LAN Ethernet.

Laptop shall be NFS server for a small board, like Pi. Right now I am operating with GUI Network manager and set a fix IP to my enp3s0 (why not eth0 ???).

As metric seems to be higher than WLAN, from that moment I don't have connection to internet. I am not a network guru, but what I found after several hours - it helps to change routing that way:

sudo route add -host <IP BOARD> (192.168.3.102) dev enp3s0
sudo route del -net 192.168.3.0 netmask 255.255.255.0 dev enp3s0

That has a few drawbacks. As ethernet setting disappears as soon as LAN connection is off, it takes a while until connection is re-established. You know, a testboard will often be repowered ;)

Even worse is, that I have to type routing commands again and again. So two questions:

• How can I setup Ubuntu 16.04 such that the LAN keeps its setting even if not wired? (Read about NetworkManager.conf, but ignore-carrier seems not to be a valid setting).
• Where and how can I make this routing information static, so that I don't have to type it in again and again?

Routing table after connection LAN of Laptop with board is:

default 192.168.3.1 0.0.0.0 UG 100 0 0 enp3s0
default 192.168.3.1 0.0.0.0 UG 600 0 0 wlp2s0
link-local * 255.255.0.0 U 1000 0 0 wlp2s0
192.168.3.0 * 255.255.255.0 U 100 0 0 enp3s0
192.168.3.0 * 255.255.255.0 U 600 0 0 wlp2s0