Difference between revisions of "Hacks, hints, and tricks"

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To use a plug-in USB serial port with screen, you need to be part of the "dialup" group.  
 
To use a plug-in USB serial port with screen, you need to be part of the "dialup" group.  
  
−
  sudo vigr
+
  sudo adduser <username> dialup  
−
 
 
−
And add your username to the end of the "dialup" line
 
−
 
 
−
sudo vigr -s
 
−
 
 
−
And add your username yet again to the end of the "dialup" line
 
  
 
Exit, and log back in. You should be able to do something like
 
Exit, and log back in. You should be able to do something like
Line 37: Line 31:
 
and use the USB serial adapter you just plugged in.
 
and use the USB serial adapter you just plugged in.
  
−
==Bluetooth pairing==
+
==Bluetooth pairing (deprecated)==
 
Some keyboards don't have a fixed PIN. To pair with them, edit the bluez-simple-agent program:
 
Some keyboards don't have a fixed PIN. To pair with them, edit the bluez-simple-agent program:
  
Line 65: Line 59:
  
 
  bluez-test-input connect [your mac address] yes
 
  bluez-test-input connect [your mac address] yes
 +
 +
==Bluetooth Pairing (use this one)==
 +
 +
Remove any old bluetooth configuration directories:
 +
 +
sudo rm /var/lib/bluetooth
 +
 +
This is particularly important if you're switching to a new bluetooth host. For some reason re-pairing a device will not work until this directory is deleted.
 +
 +
Run bluetoothctl:
 +
 +
sudo bluetoothctl -a
 +
 +
You may have to power on the host controller using the "power on" command.
 +
 +
Find the device to pair with.  It should be listed.  Otherwise, start a scan.
 +
 +
Pair the device.  Note that tab-completion works, and makes things helpful.
 +
 +
pair [your mac address]
 +
 +
The console will give you the PIN code of the keyboard.  Type this on the keyboard and hit Enter.
 +
 +
Trust the keyboard:
 +
 +
trust [your mac address]
  
 
==Getting date and time to work==
 
==Getting date and time to work==
Line 78: Line 98:
 
   
 
   
 
  sudo apt-get install ntpdate
 
  sudo apt-get install ntpdate
 +
 +
==Novena USB hub==
 +
See [[Novena-usb-hub]]
 +
 +
==Startup scripts and systemd==
 +
See https://support.criticallink.com/redmine/projects/arm9-platforms/wiki/Linux_Startup_Process_-_Systemd for help.
 +
 +
==exagear and skype==
 +
Grab the debian version of x86 skype and install under exagear. dpkg will fail but use sudo apt-get install -f to fix the dependecnies. This will subsequently break dbus on the host machine. Fix this using the following command line:
 +
 +
sudo systemctl disable exagear-guest-debian-7
 +
 +
==Enabling eepromoops==
 +
EEPROM has to be added to the device tree in order to enable eepromoops.
 +
 +
Here's the entry:
 +
 +
&i2c3 {
 +
    eepromoops@56 {
 +
        compatible = "kosagi,eepromoops";
 +
        reg = <0x56>;
 +
  };
 +
};
 +
 +
==Novena laptop front panel==
 +
 +
The front panel has two red buttons. The leftmost is used for booting and shutting down the system. The one on the right has no predefined purpose, but can be configured as desired by the user. When pressed it emits the X event "XF86Tools". E.g. the output from xev:
 +
 +
...
 +
KeyPress event, serial 37, synthetic NO, window 0x2400001,
 +
  root 0xe9, subw 0x0, time 2653630, (903,-64), root:(1774,397),
 +
  state 0x0, keycode 179 (keysym 0x1008ff81, XF86Tools), same_screen YES,
 +
  XLookupString gives 0 bytes:
 +
  XmbLookupString gives 0 bytes:
 +
  XFilterEvent returns: False
 +
  ...

Latest revision as of 16:56, 5 January 2016

A resting place for important technotes that don't fit anywhere else.

Hacks

I2C debugging

The kernel will lock I2C devices, making it impossible to use userspace tools to debug an issue. To get around this, modify drivers/i2c/i2c-dev.c and remove the EBUSY return statement. E.g. there's a function that either returns 0 or -EBUSY, make it always return 0.

Then you can use the i2c utilities to access devices that are in use.

Linux kernel debugfs

/sys/kernel/debug

contains helpful debugging infos. To mount this, use this command (assuming you've compiled in said support): 

mount -tdebugfs none /sys/kernel/debug

Hints

Building a u-boot script

mkimage -T script -C none -n 'Novena Boot Script' -d boot.txt boot.scr

boot.txt is the non-binary gook extractable from boot.scr, or you can look at the git repo to retrieve it.

Using a serial port

To use a plug-in USB serial port with screen, you need to be part of the "dialup" group. 

sudo adduser <username> dialup

Exit, and log back in. You should be able to do something like 

screen /dev/ttyUSB0 115200

and use the USB serial adapter you just plugged in.

Bluetooth pairing (deprecated)

Some keyboards don't have a fixed PIN. To pair with them, edit the bluez-simple-agent program: 

sudo emacs /usr/bin/bluez-simple-agent

and replace ‘KeyboardDisplay’ with ‘DisplayYesNo’.

This will cause the agent to display the PIN code you have to enter, instead of assuming it's fixed at 0000.

Then you can run 

hcitool scan

Pick out the MAC of the device, and run 

bluez-simple-agent hci0 [your mac address]

This should pair the two, to unpair you can do 

bluez-simple-agent hci0 [your mac address] remove

Now you have to "trust" the device: 

bluez-test-device trusted [your mac address] yes

And finally, connect it: 

bluez-test-input connect [your mac address] yes

Bluetooth Pairing (use this one)

Remove any old bluetooth configuration directories:

sudo rm /var/lib/bluetooth

This is particularly important if you're switching to a new bluetooth host. For some reason re-pairing a device will not work until this directory is deleted.

Run bluetoothctl: 

sudo bluetoothctl -a

You may have to power on the host controller using the "power on" command.

Find the device to pair with. It should be listed. Otherwise, start a scan.

Pair the device. Note that tab-completion works, and makes things helpful. 

pair [your mac address]

The console will give you the PIN code of the keyboard. Type this on the keyboard and hit Enter.

Trust the keyboard: 

trust [your mac address]

Getting date and time to work

The system should get date/time automatically when you get an IP address.

If that's not happening, do the following: 

sudo rm /etc/udev/rules.d/70-persistent-net.rules

This will remove anything that's interfering with getting the DHCP client to work.

Also make sure that this package exists 

sudo apt-get install ntpdate

Novena USB hub

See Novena-usb-hub

Startup scripts and systemd

See https://support.criticallink.com/redmine/projects/arm9-platforms/wiki/Linux_Startup_Process_-_Systemd for help.

exagear and skype

Grab the debian version of x86 skype and install under exagear. dpkg will fail but use sudo apt-get install -f to fix the dependecnies. This will subsequently break dbus on the host machine. Fix this using the following command line: 

sudo systemctl disable exagear-guest-debian-7

Enabling eepromoops

EEPROM has to be added to the device tree in order to enable eepromoops.

Here's the entry: 

&i2c3 {
   eepromoops@56 {
       compatible = "kosagi,eepromoops";
       reg = <0x56>;
  };
};

Novena laptop front panel

The front panel has two red buttons. The leftmost is used for booting and shutting down the system. The one on the right has no predefined purpose, but can be configured as desired by the user. When pressed it emits the X event "XF86Tools". E.g. the output from xev: 

...
KeyPress event, serial 37, synthetic NO, window 0x2400001,
 root 0xe9, subw 0x0, time 2653630, (903,-64), root:(1774,397),
 state 0x0, keycode 179 (keysym 0x1008ff81, XF86Tools), same_screen YES,
 XLookupString gives 0 bytes: 
 XmbLookupString gives 0 bytes: 
 XFilterEvent returns: False
 ...
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