Background to Buying a Linux System

My family switched to all-Linux in 2002. Mid-2004 was the last time I purchased a Windows license for personal use; though I have a copy of XP that I still occasionally load in a VM. 2004 was the year I bought an HP laptop that came with Windows, and I put Linux on it during its first boot. Since then I have purchased a Lenovo Thinkpad and four Dells with Linux pre-installed. It is infuriatingly difficult to avoid the Microsoft Tax, but it is possible. A lot of vendors offer FreeDOS systems these days. More important than not paying Microsoft (and more difficult) is finding a machine with Linux pre-installed.

This is not as difficult as it was. Not long ago, the only way to obtain a machine pre-installed with Linux was to purchase from a reseller like Emperor Linux. These resellers don’t have the resources of the manufacturer, and they likely paid the Microsoft Tax for you before they put Linux on the device. However, options are gradually improving. The manufacturers have experimented with Linux systems and HP, Lenovo, and Dell all sold consumer equipment pre-installed with Linux in the recent past. (I hear Sony does too, but I refuse to buy Sony products given their history of proprietary technologies, root kits, etc.) Unfortunately, all these manufacturers stopped selling the systems after a short time. After a couple of failed experiments, Dell seems to have figured things out and turned into a reliable Linux distributor with a decent selection of systems. Here is the secret to buying a Linux system from Dell: many of the best Linux configurations are only available when using the “Small and Medium Business” section of their site; the open source offerings page does not list all of their Linux offerings. The rest of this blog post details the other sad secret: Linux systems from Dell don’t necessarily play nicely with Linux.

Before we proceed, I should point out three reasons why it is worth putting in the effort to get a system with Linux pre-installed:

• Since the manufacturer is willing to support Linux running on the hardware, it is reasonable to expect that it should be easier to configure with Linux than other equipment.
• Being officially counted as a Linux user sends a direct message to the market that manufacturers should support Linux.
• Buying a machine with Linux pre-installed confers moral superiority.

Okay, so the second and third reasons are probably imaginary. I am sorry to report that the first reason is largely a fiction as well. It would be more accurate to say: since the manufacturer is willing to support Linux running on the hardware, I know that someone, somewhere got Linux to at least sort-of run.

Notice that saving money is not on the list. I am not sure what back-room deals make it as expensive to buy a machine installed with Redmond’s proprietary OS as it is to purchase a freely available OS like FreeDOS or Linux, but that is how Dell’s pricing model currently works. In other words, at the current time paying the Windows Tax, and then putting Linux on yourself is just as economical a decision as purchasing Linux pre-installed. This is good for Emperor Linux.

Buying a Dell

Dell has been shipping systems pre-installed with Ubuntu for over two years now. The ten minutes I spent playing with the stock OS were impressive. However, I choose to reinstall with the latest stock Kubuntu release for a few reasons:

• I am a control freak and want to know exactly what is on the system.
• I am a KDE fan, and Dell ships Gnome by default.
• The Dell releases are pretty old (they are still shipping 8.04).
• I don’t see much value in having an officially licensed DVD and MP3 player, though others might.

I bought an Inspiron 530 with Ubuntu over eighteen months ago. It took stock Kubuntu flawlessly and has run great the entire time. It has been the perfect Linux desktop for my kids’ machine. I highly recommend this product.

I have purchased two Inspiron Mini 10v netbooks with Ubuntu since last September. I really like these machines. They took stock Kubuntu okay—you have to install a binary blob for the wireless card (you can get the details in the Mini 10 section below), but everything else worked out-of-the-box. They are reliable machines, though I hated the touchpad for a long time. After three months I am starting to get used to it. These machines are so great that I can’t seem to keep them—family members keep buying them from me and then I have to order myself another.

I was so happy with my previous experiences that I decided to buy the top-of-the-line Linux netbook: the Inspiron Mini 10. This model must be purchased through the “Small and Medium Business” website. It has a much nicer screen, a multi-touch touchpad, faster processor, and more memory. However, getting stock Kubuntu to work on it was not as easy as I expected. Here are the details.

Kubuntu on a Dell Inspiron Mini 10

Proprietary drivers: bringing the pains of Windows to Linux!

Though I don’t know the exact reason Dell ships their Linux netbooks with a lot of binary-only proprietary drivers, I suspect that it has to do with their desire to pack in as much power per battery mWh as possible. The Mini 10 series does have impressive battery life—I am constantly surprised at how long I can go without plugging in (I plug it in most nights and haven’t run out of juice yet). I guess that Dell feels like the only way to achieve that is to use the Intel Poulsbo Chipset that requires a proprietary graphics driver. I suspect similar logic is behind the awful Broadcom wireless card as well.

Broadcom wireless driver

These Dell netbooks are not very useful until you get wireless networking setup. I had to install using a wired connection for both the Mini 10 and the Mini 10v. It is then necessary to setup the binary Broadcom driver. My understanding is that the new Jocky hardware tool will take care of this once all the correct packages are pulled down, but I am more comfortable with the command line.

aptitude install dkms patch bcmwl-kernel-source b43-fwcutter

That command is all it takes, but I’ll offer a little bit of explanation:

• dkms: This is the Dynamic Kernel Module Support framework. It is a really nice way of making sure that picky kernel modules are always correctly built against the currently running kernel. Not only does this make binary drivers easier to manage, it also solved my constant problems with updates breaking VirtualBox (on my development box—I would not recommend running VirtualBox on these netbooks).
• patch: This is required for the script to edit the bcmwl package before compilation. It should really be a dependency. It took me a while to realize the error I was getting was due to patch not being installed.
• bcmwl-kernel-source: This is the proprietary driver for Broadcom wireless cards.
• b43-fwcutter: This is a tool to install the binary blob into the Broadcom 43XX firmware. I’m not certain that it is necessary. I installed this before I realized that the DKMS driver was failing to build because of the missing patch dependency. I suspect that I would have eventually had problems if I hadn’t installed this tool.

As part of the install, dpkg correctly compiled the kernel module, inserted the binary blob, and got everything setup. KNetworkManager appeared to see the wireless at that point, but KNetworkManager hates my WPA2 setup, so I always use wicd. Don’t forget to manually tell wicd that eth1 is the wireless interface, or wicd will report that no networks are found even though iwconfig will work and wlist scan will show networks.

Sound

Remember to turn up the volume of the PCM channel.

Multi-touch touchpad

Works great:

• 1 finger tap: left click
• 2 finger tap: middle click
• 3 finger tap: right click
• place 1 finger, drag one finger: scroll (vertical only)

I don’t currently have horizontal scroll or pinch zoom working.

Video

The biggest let down with the Dell Mini 10 is the Intel Poulsbo chipset. The larger resolution of the 10 is the most appealing feature to justify the upgrade from the 10v. Unfortunately, Intel didn’t open source the driver like they have with their other GPUs because the Poulsbo is based on third party technologies. If you think the Intel name will guarantee good Linux support, you are mistaken. Ars Technica has a good rundown on the problem.

The summary is that the binary driver is only supported by Dell on the versions of Ubuntu that they are shipping. Getting packages for other versions and distributions is challenging and not very reliable. However, I was able to get the driver to work on Kubuntu Karmic Koala (9.10).

Here are the basic steps, distilled from a Launchpad Bug Report:

1. Add this PPA to ”/etc/apt/sources.list”:

   deb http://ppa.launchpad.net/lucazade/gma500/ubuntu/ karmic main
   deb-src http://ppa.launchpad.net/lucazade/gma500/ubuntu/ karmic main
   

2. Get this missing package: wget xorg-video-psb.deb. Install it with dpkg -i.

3. Run this command:

   aptitude update; aptitude install psb-kernel-headers psb-kernel-source psb-modules psb-firmware libdrm-poulsbo1 poulsbo-driver-2d poulsbo-driver-3d xpsb-glx
   

4. Create this file: “/etc/X11/xorg.conf” with these contents:

   Section "Device"
           Identifier "Configured Video Device"
           Option "IgnoreACPI"
           Option "AccelMethod" "exa"
           Option "MigrationHeuristic" "greedy"
           Option "NoDDC"
           Driver "psb"
   EndSection
   
   Section "DRI"
       Mode 0666
   EndSection
   
   Section "Monitor"
           Identifier "Configured Monitor"
   EndSection
   
   Section "Screen"
           Identifier "Default Screen"
           Monitor "Configured Monitor"
           Device "Configured Video Device"
   EndSection
   
   #Added for mouse pad
   Section "InputDevice"
           Identifier "Mouse0"
           Driver "synaptics"
           Option "Protocol" "auto"
           Option "Device" "/dev/input/mouse0"
           Option "ZAxisMapping" "4 5 6 7"
           Option "CorePointer"
           Option "HorizEdgeScroll" "1"
   EndSection
   

5. Reboot

Once it all works, you are rewarded with a very nice display which makes the netbook significantly more usable.

HDMI out

Video worked fine after enabling the external display with xrandr.

I couldn’t get audio working. Here is what I tried:

• Unmuted the IEC958 channel in alsa-mixer (and enabled it in KMix to be sure.
• Changed the device order in System Settings -> Multimedia.

Remaining problems

• Enabling desktop effects completely broke KDE. I had to revert to a backup.
• The driver cannot keep up with a full screen Hulu video, even when the video was fully buffered and at a non-HD resolution.
• The panel that is the top menu for Kubuntu Netbook Remix cannot be resized. On the high resolution screen the lock / logout buttons are very tiny and cannot be configured to be any bigger.
• I am getting lots of these errors: hda-intel: spurious response 0x0:0x0, last cmd=0x . . . but I don’t see any negative effects.

Conclusion

I am undecided whether the Dell Mini 10 is worth the hassle. I really like the multi-touch touchpad, the additional RAM, and the bigger memory. On the other hand, the significantly cheaper Mini 10v just works. If Intel and Dell could get the video driver problems ironed out, this netbook would be great.

For the last ten years I have mentally divided the computing world into three camps:

1. The sorry masses of Windows users who don’t realize that happy alternatives exist to their computing purgatory.

2. The camp of OSX users who enjoy their addiction to beautiful and functional proprietary technologies.

3. The free and dis-organized Linux users who will conquer the world once some usability issues are resolved.

As a solid member of the third camp, I have frequently suggested to my Windows using associates that their complaints will most easily be resolved by throwing their lot in with Steve Jobs and buying a Macintosh. When family and friends have needed help with computer problems I have stepped in to solve their problems, while reserving the right to complain as long as they use Windows. If they would switch to OSX or Linux I promised to stop complaining. Of course I fully expected my support burden to drop in the process.

Over the past two years five friends have taken me seriously and tried to kick their Windows habits. Three switched to Linux and two bought Macs. My preconceptions have been challenged and my comfortable world view has been shattered. The summary is that OSX let me down. I am mentally reeling from the surreal experience of hearing myself recommend replacing OSX with Windows 7.

Case Study 1:

My mother-in-law needed a computer while hers was in storage. I set her up with an account on my Kubuntu box. For two months she seemed to use OpenOffice and Firefox just fine, and didn’t seem to need much help. However, she felt very uncomfortable with it and switched back to her Windows XP/Microsoft Office machine at the first opportunity. Chalk one up for habit and Windows XP. I expect that she would struggle even more with Windows 7 and Microsoft’s new ribbon UI.

Case Study 2:

About a year ago I helped my neighbor replace his malware infected Windows machine with Linux. I was confident that Linux would be functional for him, but I expected I would need to provide some hand-holding for a while. I was pleasantly surprised that he hasn’t needed more than the initial brief orientation. The other day I asked how he was liking the setup. He said that it is great—he was working on ripping his DVDs so that he doesn’t have to worry about his little brother scratching the disks. He really enjoys being able to download tons of free software from a trusted repository of packages.

Case Study 3:

Two months ago I bought a Dell netbook pre-installed with Linux for my wife. When my sister saw it, she liked it so much that she got one too. I reinstalled the 8.04 Ubuntu that Dell provided with the pre-release Kubuntu 9.10 netbook remix. I think she only uses Open Office Writer, Firefox, and the basic card games. She appears genuinely pleased. She has only had a problem twice, and both times it was easily solved over the phone. Her system was in a weird state, and I coached her through opening a terminal and typing the proper voodoo. It was much easier than talking someone through deleting settings files from XP’s Document and Settings. (I recently tried to delete settings files from Windows 7, and I didn’t even find where they are stored.)

Case Study 4:

My brother needed a new laptop and heeded my advice that he should by a MacBook Pro. I set him up with XP in a VirtualBox so that he could still interact with his customers who are hooked on Microsoft Office. His initial impression was very positive, but over time the different key bindings drove him crazy. He never really understood how to interact with the virtual machine either. Learning the OS appeared to require more energy than he cared to invest, so he gave the Macbook to his sister-in-law and bought a Thinkpad with Windows XP. I didn’t find out for couple of months. Chalk another one up to Windows XP and force of habit.

Case Study 5:

My Dad’s Windows XP installation got a corrupted registry and wouldn’t boot to anything but safe mode. He is definitely a power user, and uses a lot of industry specific applications that only run in Windows. He also feels chained to Microsoft because at work he collaborates heavily with a team standardized on Microsoft tools. Yet his frustration with Microsoft was so great that he bought a beautiful new iMac and VMware Fusion. I explained to him that the next time his machine crashes we can roll back from a snapshot and recover in only a couple of minutes instead of a couple of days.

I wish that I had this laptop reliability study when we bought the iMac. I turned down AppleCare with the logic that the high price of a Mac was due to its superior quality. In a perfect world a manufacturer will build reliable products, rather than require users to purchase expensive service plans to have a positive experience with their brand. How naive—it’s all marketing. Apple machines are not significantly less likely to fail than non-Apple machines.

I have spent more time tinkering with OSX on this machine than I care to admit. My initial impressions were largely positive, but as I actually tried to use the machine I was disappointed. It has a Unix-like feel, yet lacks the configure-ability that I have enjoyed while using Linux. After some more use, I have come to appreciate the fine architecture of OSX. Too bad the machine is a piece of junk.

This iMac has been nothing but trouble.

Timeline

• Things worked well for a couple of months and I was optimistic that the problems we encountered were due to the adaptation to a new OS.
• A month after the one-year warranty expired I realized that the problems were probably related to a failing hard drive. Given Apple’s unwillingness to stand behind their product, I replaced the drive myself. I was optimistic that the system would now be reliable.

• Three months later the machine failed to boot. It was clearly a hardware problem. I was afraid the entire motherboard was fried. As I got price quotes I found that:

  • Apple certified support people are very overpriced.
  • Apple certified support people will not look at a machine in less than three days. APPLE: THIS MACHINE IS USED FOR BUSINESS! (sorry for raising my voice)

  I guess my mistake was treating a Mac like something more than a toy.

  If I am going to be paying a mint for the machine, and a mint for “properly trained” technicians to work on it, how come the empirical evidence does not show a corresponding increase in reliability?

• The hardware finally seemed stable, but the machine still suffered from weirdness with the keyboard and mouse. We upgraded to Snow Leopard and the weirdness appeared to go away. Except that it actually got worse. The machine is normally reliable, but a couple of times a week it just stops accepting input from the keyboard or mouse. A reboot of the system is required to get things functional again. That is a real productivity killer.

• Yesterday I did the unthinkable and I recommended that my father install Windows 7 on his iMac because I think it will solve his constant problems (did I really just say that?!?). Dad doesn’t want to give up on the Mac yet, so we tried upgrading VMware Fusion to 3 tonight; he suspects the keyboard was going dead when it would leave the virtual machine. Anything else bad happens and I’m throwing in the towel. I fully expect to be putting Windows on the box before the year’s end.

Side Note:

I helped a co-worked install a development environment on his Windows 7 thinkpad. For a Microsoft OS, I’m impressed. It feels a lot more Unix-y than previous versions. That doesn’t mean I like it. It still has the same problems with a lame terminal, no good utilities, a find that doesn’t search everything, and reliance on code pages for internationalization. Oh, and the poor security model and lameness incarnate that is the registry. On the whole, it’s a step up.

Conclusion:

My conclusion is that Linux is the only viable operating system. Thank goodness for the usability gains the Linux community have made in the last three years.

Current scorecard is: Windows XP—2, Windows 7—1 (tentative), Linux—2, OSX—Zilch.

There is probably still a niche for OSX, but my unscientific anecdotal evidence shows that for common users Ubuntu is a more practical alternative to Windows than OSX. If specialized applications prevent a switch to Linux, using Windows 7 might be better than trying OSX.

Oh Apple, how you have failed me!

I am about to start a big project for work, and I wanted to get the latest tools on my machine because I know I won’t have the opportunity for a while. Unfortunately, my install of Kubuntu Hardy 8.04 is starting to feel behind-the-times and the latest versions of my applications are getting increasingly hard to install as they depend on newer libraries. However, I have been very nervous to upgrade. I love KDE 3.5; it is a nearly perfect mix of stability, configurability, and usability; perhaps I’ve just grown very used to it. I avoided upgrading to the unfinished KDE 4.0, and have been following KDE4 closely while waiting for it to get complete enough not to drive me crazy. It looks almost there. So last week, when the project start got delayed yet again, I tackled upgrading to the freshly released Alpha 6 of Kubuntu Karmic.

Now I understand that alpha-quality software is not for production use. I also understand that the jump from KDE3 to KDE4 is a big one. However, Karmic is coming along nicely, and Alpha 6 looks almost there. My logic went like this: get the reinstall out of the way, upgrade to ext4, get used to KDE4, get the configuration file merging headache out of the way, and get everything working in the KDE4 version of my most important apps. Then it should be easy to aptitude dist-upgrade through the betas to the release even in the middle of a firestorm.

I expected this project would take a day or two, and it went more or less according to plan, but the experience was more painful than I expected. Perhaps my notes might help out others.

Before upgrading I did some due diligence. I checked the bug database, and didn’t see anything that would obviously effect me. I reviewed the development mailing list logs. Finally, I hung out on IRC for a couple of days and got opinions on the stability of the development branch. At that point I had collected enough courage to jump in.

Impressions of Karmic

For me the big change from Hardy to Karmic is KDE4. However, I did notice:

• The installer is really fast and easy to use.
• The system boots far faster.
• There is no more grub screen by default.
• I have a bunch of new folders in my home directory that I don’t need and don’t want: Documents, Pictures, Videos, Templates. The Desktop folder is being deprecated. And now they make me use a Download folder (instead of sticking it in Desktop). I’m sure this can all be configured away.

Impressions of KDE4

Summary

It is usable, but not yet as good as 3.5.

Plasma

My first impression of plasma was overwhelmingly negative. I could appreciate the configurability, but found it exceptionally painful to get things organized in a way that supported my preferred workflow. I find plasma’s interaction between panels, activities, dashboards, and virtual desktops to be too complex—especially on my dual monitor setup. It’s a lot simpler with the “one activity per virtual desktop” setting introduced in KDE 4.3, but it still isn’t intuitive. Riddle-me this: 3 virtual desktops across 2 monitors with 1 separate dashboard equals 8 activity panes. It also isn’t obvious what will happen when I disconnect a display. I suspect some of the confusion is related to inconsistent behavior as a result of bugginess.

I also find plasma to be slower than KDE 3.5. Again, it is mostly the effect of zooming out to configure my activities and desktops (the slowness contributes to the feeling of bugginess). It doesn’t seem as snappy and responsive. On the other hand, there are lots of nice effects and they run a lot faster than equivalent effects under the compiz setup I played with previously (and then turned off). The effects are well integrated into system settings and much easier to navigate and tweak than under compiz.

Perhaps the problem with plasma is just having non-intuitive defaults. Things got easier once I deciphered the nomenclature (the weirdest is how they call the “edit plasmoid bubble” a “cashew”; while figuring out the desktop I started feeling an overwhelming urge to get a snack). I started over by deleting all my activities and I let the “one activity per virtual desktop” button set everything up for me. I think I had gotten myself into a bad state while playing around. Now that I’m actually able to use the setup, plasma is really growing on me. It does make it easy to do things that were previously hard to conceive.

I think the paradigm can be just as useful and a lot simpler by merging the idea of activities and virtual desktops. There should then be an option for “virtual desktop per monitor” or “virtual desktop across all monitors”.

Scorecard

Problems with Clean Solutions

• Kopete fails to connect to Google Talk. Workaround: aptitude install qca-tls.
• KNetworkManager doesn’t like WPA on my access point. Workaround: use wicd. Bug#: 434342
• Default weather widgets won’t search for my city. Workaround: use plasma-widget-weatherforecast. Bug#: 434254
• The change monitor button (Fn-F7, a.k.a. the video button) didn’t work on my ThinkPad T61. This is the same as previous version of Ubuntu (but the monitor naming changed a little bit). Thinkwiki has a solution. Essentially, drop the script into /usr/local/bin, and create a file in /etc/acpi/events/ibmvideobtn that says:
  event=ibm/hotkey HKEY 00000080 00001007
action=/usr/local/bin/thinkpad-fn-f7
  A copy of the script is here.

Problems with Ugly Workarounds

• Logging out crashes X and takes the keyboard with it. Workaround: reboot. Bug#: 428662
• Can’t unlock screen. Workaround: run killall kscreenlocker from a virtual terminal. Bug#: 434276
• Spaces break bash tab completion. Workaround: prepend command with a slash (). Bug#: 419509
• Kopete won’t connect to jabber through a CNAME. Workaround: Use the A record or IP address. Bug#: 434214
• Kmail can’t pass options to GVim. Workaround: use gvim -f %f as the command and lose the options. Bug#: 434180
• Weird cups problems where cupsctl wants a password on bootup, and then reports “unathorized”. This is easy to ignore, but I got another authorization error while trying to install one of my printers—it reported my password as incorrect. It turns out that temporarily disabling apparmor with /etc/init.d/apparmor stop allowed me to get the task done. Debian Bug#: 543468.
• Corner actions in SystemSettings→Desktop→Screen Edges conflicts with the ones in SystemSettings→Desktop→Screen Saver→Advanced Options. I didn’t log this one.

Annoying Missing Features

• Severity 1: It does not appear to be possible to get the Application Launcher to display under the mouse pointer through a click on the background. I use this all the time, and it drives me crazy to have to move my mouse all the way to the panel on the edge of my dual-monitor widescreen display. Typing it makes it sound petty, but it drives me nuts.
• Severity 4: Konsole doesn’t save a default window size anymore. Whatever size my last closed window has is the size the next one will open with. It’s annoying because I like my terminals to be exactly half of my screen, but sometimes I will adjust it for a specific task. Now every time I adjust it I have to fiddle it back.

Summary

The good news is that in my judgment KDE 4.3 has only one really annoying missing feature. That means that KDE 4.3 is pretty feature complete in comparison to KDE 3.5. Now that I’ve got a usable system, I’m really happy with it. Though this is definitely a usable alpha, I am anxiously looking forward to the final release of Karmic Koala. Hopefully it will include fixes to some of these problems.

Getting Back to Work

Of course the moment I pass the no-turning-back point of the upgrade, I got notified of the start of my project. That means that messing with the alpha has put me behind schedule. I’d better stop submitting bug reports and buckle-down to put my shiny new tools to work.

HP has led the printing industry in providing open source software to support its printers. This makes it really easy to access advanced features of an HP printer in Linux. The difficulty for me was with the terminology:

• CUPS: UNIX printing system. CUPS manages printers and print jobs. Software talks to CUPS, and CUPS talks to a printer.
• HPLIP: HP system for running HP devices. HPLIP creates a CUPS backend to talk with a specific printer. It can also manage scanning, faxing, and copy functions of those printers.
• HPIJS: HP printer driver. Despite the name, it runs some HP laser printers too.
• Foomatic: Connects CUPS to the printer driver (HPIJS in this case), using a PPD file.
• PPD file: A Postscript Printers Description file, which describes a postscript printer to CUPS. Despite the name, it appears that non-postscript printers also need PPD files to work with CUPS.

Before the printer will work, all these components need to be installed and working. These commands should pull in all the necessary packages:

aptitude install cupsys cupsys-bsd
aptitude install hplip hplip-ppds
aptitude install foomatic-db-hpijs

Then setup the printer using cups and the hplip backend:

1. Go to http://localhost:631
2. Select Manage Printers
3. Select Add Printer
4. Select the hp device backend for your printer, not the USB or parallel backends. The URI should start “hp:”.
5. Select the HPIJS driver (PPD) for your printer. If you installed the hplip-ppds, your specific printer should be listed.
6. Print a test page.
7. Once CUPS sees your printer, you can use hp-toolbox to access your printers advanced features. hp-toolbox can not see your printer if CUPS can’t see it.

Tips for solving problems:

• Does “cat /proc/bus/usb/devices” show your printer? Check your USB connection.
• Does “hp-probe” show your printer?
• Does “hp-info” show correct information about your printer?
• Does “hp-toolbox” see your printer?
• Check that CUPS is set up to use the HPLIP queue.
• If you increase the log level to “debug” in /etc/cups/cupsd.conf and restart cupsys, do you get any better error messages in /var/log/cups/error_log?
• CUPS has the habit of outputting lines of useless messages after it describes the true cause of the error.
• Read /usr/share/doc/hplip/README.Debian.gz