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Widescreen Laptop

Question:

I have just got a Lenovo T61 with Ubuntu 8.04 installed on it. It is the widescreen model, and the Ubuntu is great … all except for one important detail. The PC projectors I have to use when I visit businesses to make presentations are not widescreen. I  ave tried to set the screen resolution to 1024x768 (or other screen resolutions that are non-widescreen), but strangely, Ubuntu shows the screen limit at the new resolution, but the background image of the heron covers the whole of the widescreen beyond the border of the screen resolution I have just set.

When I run OpenOffice Impress in SlideShow mode, Impress fills the whole widescreen and leaves the PC projector only showing part of the image, even though I have the laptop set to the non-widescreen resolution of 1024x768. How can I get the laptop to work properly with the PC projectors?

I enjoy your column every month in Linux Pro Magazine.

Answer:

Notebooks and projectors have always been a disaster. The problems you describe are not even as bad as other things that can happen. Effects range from cut-off borders of the screen, wrong resolution, or no picture at all, to totally unusable resolutions and even frozen screens. It turns out to be a hardware problem: Showing a picture on the computer's internal display at the same time as on the projector is apparently a very difficult job for chipset designers.

I found that on a variety of small notebooks – namely those with a small resolution on the internal display – the quickest and best results can be obtained by switching off the internal display while adjusting the resolution for an external projector.

The program Xrandr can help you do this. You should call it from a script that allows you to reset back to the working internal screen resolution with a single keystroke so that you don't have to log in via SSH over the network to get the internal display back to working order. For example:

# Set projector mode
xrandr --output LVDS --off
xrandr --output VGA --auto
read -p "Hit return to get back to the internal display"
xrandr --output VGA --off
xrandr --output LVDS --auto

It is also possible to enforce a specific resolution. For the Eee PC, the only resolution that shows a picture on internal as well as external screens is 640x480:

xrandr --output LVDS --mode 640x480
xrandr --output VGA --mode 640x480

If you are running a window manager that is aware of the X ser-ver's resolution change feature (both Gnome and KDE are), your desktop will adjust to the new size automatically.

A GUI variant of this command is krandrtray for KDE, which will create an icon on the system panel that allows you to change resolutions on the fly, internally and externally, with a single click.

With some shell skills, you can build a  esolution/output toggle script with Xrandr and put it on the "change video output port" hotkey of your keyboard by modifying /etc/acpi/actions/hotkey.sh.

Connecting Mom

Question:

I am a happy Ubuntu user for the past 4 months (after using Windows since 1997).

I want to get the rest of my family on the Ubuntu/Linux train, but I have two problems:

  • My mom lives abroad. With a Window OS, I was able to help her by connecting remotely to her PC (MSN remote connection). If she were to move to Ubuntu, how would I connect remotely to her PC?
  • My wife works from home and connects with a connector to a Windows-based network in the office. Would it be possible to connect to the office network from an Ubuntu-based PC?

I hope my questions are clear. Thanks for your enlightening answers in the Linux Magazine.

Answer:

Most GNU/Linux distributions including Ubuntu have a "share desktop" feature, which is in most cases VNC (the same you can use for Windows), FreeNX, or an RDP-based tool. It allows you to connect to a running graphical session and "take over" control if the other side gives permission by sending you an invitation with a password.

The easiest and probably most secure way for remote support would be the use of SSH with X-Forwarding enabled (ssh with the -X option), which also allows you to start graphical programs over the remote connection.

Connecting to a remote "Windows terminal server" is possible with the Rdesktop client. For proprietary extensions like Citrix, client programs are available for Linux, but I would try Rdesktop first. In either case, you get a desktop window that contains a running Windows session and allows you to log in with a password and run Windows programs on the server, or whatever you do with Windows.

For just connecting to a Windows file server, a Samba client like mount.cifs is sufficient. If you need to log in via a proprietary VPN first, (k)vpnc might be helpful.

Partitions Per Drive

Question:

Can you help with the sudden change (in recent distributions) of the maximum number of partitions per drive from 64 to 15?

I have just tried to install Mythbuntu, and it simply refused to format sdb19. Previously I had tried to install SUSE and the installer started to download 3.5GB because it could not mount the DVD from which it had been loaded.

I run a multiboot system with around 30 partitions per internal drive. The production systems are all in the higher partitions. The problem seems to be caused by libata and the long-term solution means starting again with a virtualized system, and I suspect that, in practice, the same applies to LVM.

Have you any suggestions which would help in the short term?

Answer:

A few possibilities:

  • Dirty hack, but quickest method: load the loop.ko module with max_loop=32 and access partitions on /dev/sda via the losetup offset (-o) and size limit (-s) parameters. Your mountable partitions will then be /dev/loop*. Of course, you can restrict this to partitions >=16. The problem is, you will have to compute the offsets carefully by looking at the partition table, and you also have to be careful not to overwrite consecutive partitions in case of formatting (hence the size limit parameter).
  • Revert to IDE.
  • Use the logical volume manager instead of real partitions.
  • Patch the kernel.
  • For USB disks, a "use dynamic minor allocation" feature allows Udev to create new devices with dynamic minor device IDs as needed. I don't think this affects SCSI/SATA disks, though. It might be possible to activate this for SATA as well in future kernels.

The use of LVM instead of partitions is probably the cleanest solution in the long term, but it requires repartitioning, as well as backing up and restoring all data.

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  • Ask Klaus!

    Klaus Knopper is the creator of Knoppix and co-founder of the LinuxTag expo. He currently works as a teacher, programmer, and consultant. If you have a configuration problem, or if you just want to learn more about how Linux works, send your questions to: klaus@linux-magazine.com

  • Ask Klaus!

    Klaus Knopper is the creator of Knoppix and co-founder of the LinuxTag expo. He currently works as a teacher, programmer, and consultant. If you have a configuration problem, or if you just want to learn more about how Linux works, send your questions to: klaus@linux-magazine.com

  • Ask Klaus!
  • Ask Klaus!

    Klaus Knopper is the creator of Knoppix and co-founder of the LinuxTag expo. He currently works as a teacher, programmer, and consultant. If you have a configuration problem, or if you just want to learn more about how Linux works, send your questions to: klaus@linux-magazine.com

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