2016. július 15.

Shared Folders setup on Ubuntu 16.04 as a VirtualBox Guest

  1. Install the Virtual Box Guest Addition
    • from vbox menu: "Devices" --> Insert Guest Addition CD Image...
    • If you get "failed to connect to the virtualbox kernel service access denied" error message after reboot or in the future:
      1. Eject the VBOXGUESTADDITION CD image from Ubuntu
      2. Reinsert the image from the vbox menu.
  2. Add Shared Folders in vbox menu "Devices" --> Shared Folders --> Shared Folders Settings
    • check the checkboxes that apply to your needs.
    • the following part of the tutorial assumes you checked Auto-mount and Make Permanent options.
  3. Add yourself to the VBOXSF user group
    • install gnome-system-tools to get a graphical user interface for that, and then run users-admin from the terminal or "Users and Groups" from menu.
  4. Now, your shared folder should be mounted with the "sf_" prefix.
If something does not happen at once, then do a reboot.

  • https://help.ubuntu.com/community/VirtualBox/SharedFolders
  • http://www.howtogeek.com/187703/how-to-access-folders-on-your-host-machine-from-an-ubuntu-virtual-machine-in-virtualbox/
  • http://askubuntu.com/questions/456400/why-cant-i-access-a-shared-folder-from-within-my-virtualbox-machine
  • http://askubuntu.com/questions/642991/virtualbox-ubuntu-14-04-vboxclient-the-virtualbox-kernel-service-is-not-runnin

2016. január 19.

Out of 4GB RAM only 3.3GB is usable

Yesterday I bought a 2GB RAM to upgrade my HPQ TC4400 to the maximum allowed memory: 4GB. Before that I had 2+1GB installed, showing up as 2.9GB.

This 2+2GB RAM however shows up only as 3.3GB. Wow. Only 0.4GB increase. So I started to look around for the WHY?!?

Probably useful links:
  • There is actually a post about TC4400 here: http://forum.notebookreview.com/threads/tc4400-only-recognizes-3447mb-in-windows.225619/ It concludes that it was Windows' fault, and it needed an upgrade.
  • More useful info for linux:  http://superuser.com/questions/453201/only-3-2gb-of-4gb-ram-detected-on-64-bit-debian
  • Here they suggest to reinstall the 64-bit system: http://askubuntu.com/questions/32272/why-does-ubuntu-only-show-3gb-of-ram 

Another important note is that the BIOS is already the latest (Version: 68YHV Ver. F.0C; Release Date: 07/09/2008); It does not have an option for Memory Hole Remapping; The processor is Intel Pentium M Core2 CPU T5600 @ 1.83GHz and it does have a PAE (Physical address extension) flag (according to dmidecode).

I definitely have a 64-bit operating system, so the limitation cannot be due to a 32-bit OS.
~$ uname -a
Linux 3.13.0-74-generic #118~precise1-Ubuntu SMP Fri Dec 18 10:38:55 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

The maximum capacity is 4GB:
~$ sudo dmidecode --type 16
# dmidecode 2.11
SMBIOS 2.4 present.
Handle 0x000A, DMI type 16, 15 bytes
Physical Memory Array
 Location: System Board Or Motherboard
 Use: System Memory
 Error Correction Type: None
 Maximum Capacity: 4 GB
 Error Information Handle: No Error
 Number Of Devices: 2

I do have 4GB installed:
~$ sudo dmidecode --type 19
# dmidecode 2.11
SMBIOS 2.4 present.
Handle 0x000D, DMI type 19, 15 bytes
Memory Array Mapped Address
 Starting Address: 0x00000000000
 Ending Address: 0x000FFFFFFFF
 Range Size: 4 GB
 Physical Array Handle: 0x000A
 Partition Width: 2

However, there is only ~3.3GB available:
~$ cat /proc/meminfo | grep "MemTotal"
MemTotal:        3460508 kB

Free shows the same:
~$ free -m
             total       used       free     shared    buffers     cached
Mem:          3379       2673        705          0        346       1109
-/+ buffers/cache:       1217       2161
Swap:         4881          0       4881

DMSG log has more detailed info:
~$ cat /var/log/dmesg | grep "Memory"
[    0.000000] Memory: 3439500K/3530168K available (7639K kernel code, 1140K rwdata, 3512K rodata, 1360K init, 1448K bss, 90668K reserved)
[   15.528520] [drm] Memory usable by graphics device = 256M

There is something else interesting in /var/log/dmesg (opened it with gedit)
[    0.000000] x86 PAT enabled: cpu 0, old 0x7040600070406, new 0x7010600070106
[    0.000000] original variable MTRRs
[    0.000000] reg 0, base: 0GB, range: 2GB, type WB
[    0.000000] reg 1, base: 2GB, range: 1GB, type WB
[    0.000000] reg 2, base: 3GB, range: 256MB, type WB
[    0.000000] reg 3, base: 3328MB, range: 128MB, type WB
[    0.000000] reg 4, base: 64888MB, range: 8MB, type UC
[    0.000000] reg 5, base: 4175488KB, range: 128KB, type UC
[    0.000000] total RAM covered: 3456M
[    0.000000] Found optimal setting for mtrr clean up
[    0.000000]  gran_size: 64K  chunk_size: 1G  num_reg: 3   lose cover RAM: 0G
[    0.000000] New variable MTRRs
[    0.000000] reg 0, base: 0GB, range: 4GB, type WB
[    0.000000] reg 1, base: 3456MB, range: 128MB, type UC
[    0.000000] reg 2, base: 3584MB, range: 512MB, type UC

The same information can be found here:
~$ cat /proc/mtrr 
reg00: base=0x000000000 (    0MB), size= 4096MB, count=1: write-back
reg01: base=0x0d8000000 ( 3456MB), size=  128MB, count=1: uncachable
reg02: base=0x0e0000000 ( 3584MB), size=  512MB, count=1: uncachable

And then, 'smem' shows that there is ~700K reserved for the firmware/hardware... but WHY? (the "Used" amount sums up to 4194304 below)
~$ smem -R 4G -w
Area                           Used      Cache   Noncache 
firmware/hardware            733796          0     733796 
kernel image                      0          0          0 
kernel dynamic memory       1827468    1718276     109192 
userspace memory            1180160     207332     972828 
free memory                  452880     452880          0 

In comparison, when 3GB memory is in the machine, the numbers are like this:
~$ smem -R 3G -w
Area                           Used      Cache   Noncache 
firmware/hardware             72292          0      72292 
kernel image                      0          0          0 
kernel dynamic memory       2324328    2228148      96180 
userspace memory             648196     164924     483272 
free memory                  100912     100912          0

~$ free -m
             total       used       free     shared    buffers     cached
Mem:          3001       2919         81          0         26       2164
-/+ buffers/cache:        727       2273
Swap:         4881          0       4881

[    0.000000] x86 PAT enabled: cpu 0, old 0x7040600070406, new 0x7010600070106
[    0.000000] original variable MTRRs
[    0.000000] reg 0, base: 0GB, range: 2GB, type WB
[    0.000000] reg 1, base: 2GB, range: 1GB, type WB
[    0.000000] reg 2, base: 64504MB, range: 8MB, type UC
[    0.000000] reg 3, base: 4175488KB, range: 128KB, type UC
[    0.000000] total RAM covered: 3072M
[    0.000000] Found optimal setting for mtrr clean up
[    0.000000]  gran_size: 64K  chunk_size: 64K  num_reg: 2   lose cover RAM: 0G
[    0.000000] New variable MTRRs
[    0.000000] reg 0, base: 0GB, range: 2GB, type WB
[    0.000000] reg 1, base: 2GB, range: 1GB, type WB

I also tried running Ubuntu from an USB pendrive, but it shows the same amount of memory. And I tried running Windows 7, and this also shows only 3,3GB.

According to this article (http://duartes.org/gustavo/blog/post/getting-physical-with-memory/), "some of the physical memory range in an Intel computer is mapped to devices like hard drives and network cards instead of actual RAM memory. This allows drivers to communicate with their devices by writing to and reading from memory. The kernel marks these memory regions as uncacheable in the page tables." Then in the article about the Memory Map (http://duartes.org/gustavo/blog/post/motherboard-chipsets-memory-map/) it is said that "this mapping of memory addresses away from RAM modules causes the classic hole in PC memory between 640KB and 1MB. A bigger hole arises when memory addresses are reserved for video cards and PCI devices." "The diagram below shows a typical memory map for the first 4 gigs of physical memory addresses in an Intel PC:"
Then it is said that "the CPU mode determines how much physical memory can be accessed. For example, if the CPU is running in 32-bit mode, then it is only capable of physically addressing 4 GB (well, there is an exception called physical address extension, but ignore it for now). Since the top 1 GB or so of physical addresses are mapped to motherboard devices the CPU can effectively use only ~3 GB of RAM. [...] On the other hand, a CPU running in 64-bit mode can physically access 64GB (few chipsets support that much RAM though). In 64-bit mode it is possible to use physical addresses above the total RAM in the system to access the RAM regions that correspond to physical addresses stolen by motherboard devices. This is called reclaiming memory and it’s done with help from the chipset."

My conclusion is that there is no way to access all the 4GB of memory as RAM.

2016. január 14.

Notes on mounting and unmounting an Android Phone

If you do not have USB Mass Storage option any more on your Android phone to connect it to Ubuntu, but have Media Device (MTP) and Camera (PTP) instead, you have the following options:

A) You connect the phone with PTP, which works out of the box, but you'll only reach the camera related files from your device.

B) You try to hack around making MTP work to be able to reach all your files.

I went along with the latter case, and have not finished the process just yet, so I just list the pages that came along:
  • http://bernaerts.dyndns.org/linux/74-ubuntu/268-ubuntu-automount-any-mtp-device
  • http://www.mysolutions.it/mounting-your-mtp-androids-sd-card-on-ubuntu/
  • http://askubuntu.com/questions/87667/getting-mtp-enabled-devices-to-work-with-ubuntu
  • http://ubuntuforums.org/showthread.php?t=2226702
  • https://www.reddit.com/r/GalaxyNexus/comments/15uguz/automatic_mtp_mounting_in_ubuntu_guide/

2016. január 3.

Good-bye Ubuntu Phone

Today is the day when I gave up on the Ubuntu Phone. I sticked with it from May until the end of the year, updated it whenever there was a new update, but there was no significant improvement.

The main reason I quit for now is the lack of push notifications. I use my phone for communication, like probably most phone users. By sticking with the Ubuntu phone was like not having a smart phone at all. Only Gmail notifications worked, but I usually do the messaging on Facebook.
Another interestig problem was with the mobile internet connection.
I use a very limited connection for most of the time, because it is very cheap, and on an android phone I was able to stream a low bandwith internet radio with it, which is pretty much enough for me for the price. However this did not work on the Ubuntu Phone. When using this limited connection even the Gmail WebApp did not come through. (However gmail loaded through the browser, very-very slowly).

Lucky me, there is a way to convert the phone to Android, and this way at least the hardware is not wasted.
This is the tutorial: http://a25.co/ubuntu-phone-how-to-install-android/#fnref:1

2015. október 2.

Building a Plex Plugin from scratch

First of all, some important url-s for learning:
 Seconds, the skeleton  (directories and files) of a plex plugin (all are case sensitive):
  • MyPlugin.bundle
    • Contents
      • Code
        • __init__.py
      • Info.plist
An absolute minimal content of the Info.plist:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
An absolute minimal content of the __init__.py (for a responding plugin):
@handler('/video/myplugin', 'My Plugin')
def Main(): # this is the landing page of the plugin because of the prefix handler.
    return ObjectContainer()
That's it. Every plugin grows out from this root :)

Okay, one thought to developing a plex plugin: without a proper IDE, you're dooooomed! :D Okay, maybe not, but if you use other people's code than sorting out python syntax errors (like: there's a tab instead of space, and here's a comma missing, thet indentation is only 2 space not 4, etc) can be quite annoying since the Plex server does not help much with debugging (it either responds or not, but that's it).
Anyway, I managed to make my first plex plugin work... or at least some parts of it, and at least on my PC :) Here it is.

2015. október 1.

Plex Plugin Installer

So, since I found plex plugin manual installation painfully boring, I wrote a nautilus script to do the job for me.
Instead of copy-pasting, you can also download this script form github.

I wasted a couple hours finding out that  if I use "double quotes" instead of 'single quotes' when assigning the plugin folder path to the PLUGIN_FOLDER variable, then 1.) the path will break on spaces and won't work; 2.) if I surround the call with '"'-s (a double quote between two single quotes) or just another "-s the program will fail not finding the files/directories. This was the tricky part because if instead of running I echoed the lines, they looked perfectly okay, and if I copy-pasted them to the command line they would even run properly... only not within a script.

# nautilus script
# install PLEX plugin on Ubuntu 12.04.

# run this script by right clicking on the directory you want to install
install_plugin () {
 # standard feature: install by copying folder
 # future enhancement: install from ZIP file

 PARAMETERS=( "$@" )               ## array containing all params passed to the script

 PLUGIN_FOLDER='/var/lib/plexmediaserver/Library/Application Support/Plex Media Server/Plug-ins/'

 # read folder paths into TO_BE_INSTALLED
 IFS=$'\n' read -d '' -r -a TO_BE_INSTALLED < <(printf '%s\n' $PARAMETERS); unset $IFS


 for package in "${TO_BE_INSTALLED[@]}"; do
  package_name="${package##*/}" # Strip longest match of substring (*/) from front of string

 # sanity check: is the path correct? it should be a directory and end with ".bundle".
  if  [[ -d "$package" ]]; then # if selected path IS a directory
   if [[ "${package_name##*.}" == "bundle" ]]; then
   # check if plugin already exists
    if [[ -d "$installed_package" ]]; then 
     # if yes, ask to delete it 
     echo -n "A package with the same name is already installed. Would you like to overwrite it? (yes/no): "; read overwrite 
     if [[ $overwrite == [Yy][Ee][Ss] || $overwrite == [Yy] ]]; then 
      sudo rm -R "$installed_package"
      echo "You chose not to overwrite $package_name so it will not be processed."
   # install plugin
    #copy the downloaded plugin to the plex plug-in directory
    sudo cp -R "$package" "$PLUGIN_FOLDER"

    #change the permissions to be like the existing plug-ins 
    #(this is not needed in 14.04 anymore)
    sudo chmod ugoa+rx "$installed_package"

    #change the owner of the files to be like the existing plug-ins
    sudo chown -R plex:plex "$installed_package"


   else # if not "bundle"
    echo "Package name should end with '.bundle'. $package_name will not be processed."
    continue # process next package instead

  else # if not directory
   echo "Package should be a directory. $package_name will not be processed."
   continue # process next package instead

# when finished with all packages, restart plex server.
if [[ $need_to_restart_server = true ]]; then 
 sudo service plexmediaserver stop
 sleep 5
 sudo service plexmediaserver start
 echo "Installation complete. Your new plug-in should show up now in PLEX."

export -f install_plugin

gnome-terminal --execute bash -c 'install_plugin "$NAUTILUS_SCRIPT_SELECTED_FILE_PATHS"; bash'

2015. szeptember 2.

Firefox, AdBlockPlus and Ctrl+Shift+V

I use Ctrl+Shift+V (Paste as Plain Text) extensively overall. However I experienced that in Firefox instead of doing the Paste it opens a sidebar called "Blockable items on current page".

It turned out that this is because of the AdBlockPlus plugin.

To restore the Paste as Plain Text functionality you'll have to
  1. open the about:config page in Firefox, 
  2. search for the preference name extensions.adblockplus.sidebar_key 
  3. change the value of it to something else than Accel Shift V
  4. restart Firefox 
After doing these steps, you should have the Paste as Plain Text functionality back.

The solution comes from this source.