The 3 Button Serial Mouse mini-HOWTO

12. Miscellaneous Problems and Setups

• If you have trouble with your mouse in X or console mode, check you are not running a getty on the serial line, or anything else such as a modem for that matter. Also check for IRQ conflicts.
• It is possible that you need to hold down the left button when booting X windows. Some systems may send some sort of signal or spike to the mouse when X starts.
• Problems with serial devices may be due to the serial port not being initialised correctly at boot. This is done by the setserial command, run from the start-up script /etc/rc.d/rc.serial. Check the man page for setserial and the Serial-HOWTO for more details. It may be worth a little experimentation with types, for instance try setserial /dev/mouse uart 16550 or 16550a regardless of what port you actually have. (For instance, mice don't like the 16c550AF).
• The ClearDTR flag may not work properly on some systems, unless you disable the RTS/CTS handshaking with the command:

  stty -crtscts < /dev/mouse

  (Tested on UART 16450/Pentium by Vladimir Geogjaev geogjaev@wave.sio.rssi.ru)
• Logitech mice may require the line ChordMiddle to enable the middle of the three buttons to work. This line replaces Emulate3Buttons or goes after the /dev/mouse line in the config file. You may well need the ClearDTR and ClearRTS lines in your Xconfig. Some Logitech mice positively do not need the ChordMiddle line - one symptom of this problem is that menus seem to move with the mouse instead of scrolling down. (From: chang@platform.com)
• Swapping buttons: use the xmodmap command to change which physical button registers as each mouse click. eg: xmodmap -e "pointer = 3 2 1" will turn round the buttons for use in the left hand. If you only have a two-button mouse then it's just numbers 1 & 2.
• Acceleration: use the xset m command to change the mouse settings. eg xset m 2 will set the acceleration to 2. Look at the manpage for full details.
• Pointer offset: If the click action appears to be coming from the left or right of where the cursor is, it may be that your screen is not aligned. This is a problem with the S3 driver, which you may be able to fix using xvidtune. Try Invert_VCLK/InvertVCLK, or EarlySC. This info from Bill Lavender ( lavender@MCS.COM) and Simon Hargrave. In the XF86Config, it might look like this:

  Subsection "Display"
      Modes       "1024x768" "800x600" "640x480" "1280x1024"
      Invert_VCLK "*" 1
      ...
  

• If you are getting `bouncing' of the mouse buttons, ie two clicks when you only wanted one, there may be something wrong with the mouse. This problem has been solved for Logitech mice by Bob Nichols ( rnichols@interaccess.com) and involves soldering some resistors and a chip in the mouse to debounce the microswitches.
• If some users cannot get the mouse to work but some (eg root) can, it is possible that the users are not running exactly the same thing - for instance a different version of X or a different Xconfig. Check the X start-up messages carefully to make sure.
• If you find the mouse pointer is erasing things from your screen, you have a server config problem. Try adding the option linear, or maybe nolinear to the graphics card section, or if it is a PCI board, the options tgui_pci_write_off and tgui_pci_read_off. (This seems to be a Trident Card problem.)
• If the mouse cursor doesn't show up on the screen, but otherwise seems to be working, try the option "sw_cursor" in the Device section of the config file.
• If your mouse stops working when its sunny or when you turn a light on, it may be that the sensors are being swamped by light getting through the case. You could try painting the inside of the case black, or putting some card in the top.
• Microsoft Brand mice are often a cause of problems. The newest ``Microsoft Serial Mouse 2.1A'' has been reported not to work on many systems, although unplugging it and plugging it in again may help. gpm version 1.13 and higher should also support 2.1A mice, using the pnp mouse type. (See the gpm section for how to re-export this.) The ``Microsoft Intellimouse'' also causes problems, although it should now be supported by XFree version 3.3 and later.