Saturday, February 6, 2016

Fixing Lenovo U31-70 WiFi Problem


Lenovo U31-70 is a lightweight laptop. Its WiFi performance has been a headache to many people. Most people report unstable signal dropping.

For those who use Windows and are experiencing unstable WiFi problem, you just need to solve the hardware problem.

I use Linux, so I had to go a different route to solve my driver problem.

The Hardware Problem

I opened up the laptop, and found that the two antenna cables were not properly attached to the card. There was a tape (not shown in the picture) trying to keep the two cables attached, but failed due to the tension from the bending; also, the screw to attach the card onto the main board is too close to one of the antenna contacts so it automatically grounds it, making that antenna useless. This is a design problem.

I first re-attached the two cables back to their contacts and re-tape them, and put some non-conductive material between the screw and the contact to prevent the grounding. It helped.

The Atheros 10K Driver Problem under Linux

I had used several Thinkpads since its IBM days, so I was quite surprised to have found that this Lenovo's Atheros 10K chip was not supported under Linux. People were reporting stable driver performance under Windows, and some efforts were made to bring the firmware from Windows driver to Linux. I waited a few months for Linux kernel to come to version 4.3 and spent a lot of time trying various hacks to get the driver working. I was never able to get stable performance.

I decided to replace the card with Intel Dual Band Wireless AC 3160, which is well supported by native Linux.

(I have no idea which antenna cable is intended for WiFi and which is for bluetooth, but this works for me; besides, tension-wise, this is the only way I could keep the contacts isolated.)

It has been working flawlessly.

Saturday, January 30, 2016

Coordinate Transformation Matrix for Touchscreen in multi-screen setup in X11

Currently I have a twin screen setup in Arch Linux, like this:

On the left, DELL 1901FP is turned 90 degree counter-clockwise in its portrait mode. On the right, DELL P2314T, a touch screen, is in its regular landscape orientation, with its bottom line aligning with the bottom of the rotated screen on the left.

Here's my xorg.conf for that. (Although one can also setup screen arrangement in KDE/Plasma/Gnome/etc., for KDM/SDDM/GDM/etc. to recognize it in the login screen, it's important to put this in xorg.conf)

X11 sees a (1024+1920) wide * 1280 high DISPLAY, with an upper-right corner being invisible.

Since the touchscreen is just a regular pointer device (through its driver), when I put my finger on the left border of the touchscreen on the right, the cursor goes all the way to the very left of the DISPLAY. Touchscreen is only useful if the cursor follows my finger. Therefore, we need to do some Input Coordinate Transformation.

Coordinate Transformation Matrix is precisely the needed configuration.

From the documentation above, our goal is to map the following coordinates on the left (X11's default behavior) to the ones on the right:

So that means we are solving the following system:

Here's the solution:

Convert it to float numbers:

Now we can put these numbers into the configuration, as the document instructed.

However, it doesn't work. The cursor stays on the lower right. After some debugging, I found the offsets 1024 and 200 were the culprit. They need to be a percentage, i.e. relative to the full width and height.

So 1024.0/(1024+1929) = .3476766, 200.0/1280 = .15625

I put it in /usr/share/sddm/scripts/Xsetup (or /usr/share/config/kdm/Xsetup if you haven't upgraded to plasma) as well as ~/.xprofile so it automatically runs every time.

Edit 2016-02-22: I ended up having 3 screens with two in the portrait orientation. SDDM correctly uses metamodes setting in xorg.conf, regardless of the screen power. However, KDE is more sensitive to that so sometimes the layout is messed up. Here's a script to quickly correct that.

Monday, October 19, 2015

Install Sibelius 8.0.1 on a non-C drive in Windows

Since Sibelius 8.0.0, Avid changed the installer, and it has a serious bug -- it assumes you have a C: drive before letting you choose the installation destination. I figured out a hack to install it. However, it doesn't work for Sibelius 8.0.1, so here's another way to approach it, before Avid's Sibelius team fixes the bug.

I don't have a C: drive, but Sibelius insists that I must do, so what we are trying to do here is to temporarily create a C: drive, and then create a link pointing crucial directories back to my system drive, K:. After Sibelius is successfully installed, we can then safely remove the temporary C: drive.

First, we need to create a Virtual Hard Drive (VHD) as our C:\ drive. I learned how to do this via this answer:
  • Start → run → diskmgmt.msc (accept all defaults... I'm not doing anything special below) 
  • From the menu bar select Action → Create VHD 
  • Choose the location and name the file (which will be the vhd) and specify the size and click OK. My file is K:\virtual_drive_c.vhd and the size is 1G, but I made it dynamic so it's actual size is around 16MB. 
  • Right click on the Disk # (underneath will be Unknown and the size and "Not Initialized"). Select "Initialize Disk" and click OK 
  • Right click on the black bar of the unallocated disk space and select "new simple volume". A wizard opens up an on the second page it lets you assign the drive letter. We want C: here. Complete the wizard and you're done!
Now that we have a C: drive, we can link the important folders. I learned how to do that from this post:
  • Start → run → cmd, then right click and choose "Run as Administrator". 
  • In the prompt, type the following:
K:\>mklink /j "C:\Program Files" "K:\Program Files"
Junction created for C:\Program Files <<===>> K:\Program Files

K:\>mklink /j "C:\Program Files (x86)" "K:\Program Files (x86)"
Junction created for C:\Program Files (x86) <<===>> K:\Program Files (x86)

After that, Sibelius installation should run normally. In the installer, I still choose to install the program to K:, to avoid future problems running Sibelius, since the bug is on the installer, not Sibelius itself.

Afterwards, you can reboot, and safely delete the vhd file.

Thursday, September 24, 2015





我小學正是Apple II電腦剛進入台灣的時候。那時候Apple II能插一張「佳佳漢卡」來顯示中文。打字方面只有倉頡與注音。我試學了幾次倉頡,最後都放棄。主要也因為那時候打中文的機會少,所以茍且用注音好多年。


















由於上述的版權問題,軟體無法直接包含大易,所以這個過程只能手動。雖然花點力氣,也能把大易都裝上去(gcin, Lime, Open vanilla, 內建, JB/iAccess),但辛苦的是,每次系統或是作業環境升級,這個過程就得重來一次。







順道一提,這陣子我開始用手機上 Google 的中文語音輸入,準確度很高,但輸入標點符號很麻煩,而且跨平台很不方便,隱私上也有些顧慮。







Wednesday, August 5, 2015

Sibelius 8 Installation on Non-standard Windows System Drive

UPDATE: This doesn't work for Sibelius 8.0.1. See this post instead for that.

Over the years I have many generations of audio software and plugins installed on Windows, which itself has gone through many version upgrades. I can't remember why but one upgrade called for changing the system drive from C: to K: (probably for a backup reason), and ever since then K: has been my system drive.

Between projects, I decided to give Sibelius 8 a try. However, the installation file (Install_Sibelius.exe, unpacked from downloaded from Avid gave me this error:

Error 1327 invalid drive C:\.

By inspecting the log, I concluded that was hard-coded in the installer (FAIL! To tell the truth, it has been a familiar feeling ever since Avid acquired Sibelius).

I really don't want to change the system drive again, since it would involve the painful process of re-configuring a million things. It's also after their support hours so I did some research, and after some trial and error, this is what worked for me:

1. run cmd.exe as Administrator.
2. Change into the directory where Install_Sibelius.exe resides
3. Run the following command

J:\Users\composer\Desktop>J:\Install_Sibelius.exe /s /v"/qn /l*v %temp%\AvidSibeliusx64.log"

4. Follow the standard procedure to activate the software

That's it.

PS: I very much look forward to Daniel Spreadbury's new score writer.

Wednesday, May 6, 2015

X11 Multi-seat running KDE and GNOME

I was archiving data on my old machine and decided to share my old multi-seat configurations (I don't need multi-seat anymore), in case somebody out there is trying to do the same thing.

It was a 7-year-old Dell PowerEdge server SC-1430 running dual Xeon (8 virtual cores), excellent for compiling, number crunching (machine learning), and video processing (Cinelerra), and on top of all that, it served as a file/media server running RAID 5 over RAID 0.

It was a power beast, in another sense, too, though -- it consumed a lot of power.

Since it was consuming power anyway, I decided to get rid of other computers and maximize its use, by setting up a multi-seat X11, so two users could use it at the same time. There were two sets of everything: two screens (on two NVIDIA cards), two keyboards, two mouses, and two USB sound cards. It worked just like two independent machines. In fact, one seat ran KDE and the other one ran GNOME. The login screen ran KDM, with two login boxes (default to the regular user login name) on respective screens and matching wallpapers. We were even able to play "networked" game against each other.

(Actually I had three sets of xorg.conf to support multi-seat, left-side dual screen, and right-side dual screen, and I used symlinks to dynamically switch to a different configuration. However, there's more info on dual screen setups out there so I skipped those here.)

For me, there were a few files to configure. These are the ones relevant to most people:
  • /etc/X11/xorg.conf
  • /etc/kde/kdm/kdmrc
  • /etc/kde/kdm/backgroundrc.seat0
  • /etc/kde/kdm/backgroundrc.seat1
  • /etc/udev/rules.d/60-dell-keyboards.rules (omit here; see my other post on udev for that)
  • /etc/udev/rules.d/90-creative-xmod.rules
For the sound cards, I just used the GUI setup in KDM and Gnome, respectively, to choose the right pulse audio sound device. I did use the udev to make the names easier to tell them apart.

I ran Arch Linux 64 on that one so the paths may be different if you use a different distro. I apologize in advance for not explaining the details here, many of which were specific to my system back then. I also wish I had time to dig out the document sources for these configs.






Friday, March 6, 2015


(My high school homeroom teacher passed away, and this is my tribute and eulogy to him. There's no English translation.)