The Smell of Molten Projects in the Morning

Ed Nisley's Blog: Shop notes, electronics, firmware, machinery, 3D printing, laser cuttery, and curiosities. Contents: 100% human thinking, 0% AI slop.

Category: Software

General-purpose computers doing something specific

  • Kindle Fire Configuration

    Amazon obviously designed the Kindle Fire as an extension of their on-line store: they stripped everything out of Android that could possibly get in the way of buying stuff. Some functions seems obviously necessary, though, so here’s a short list of what I’ve added so far (in addition to the button protector and speaker seals, that is), with all the links collected for reference.

    First and foremost, set a Lock Screen Password. Yes, that means that you must type the password every time the Fire lights up, which is a major nuisance. Remember that the Fire connects directly to your Amazon One-Click account and the browser has the rest of your userids & passwords on tap, so losing it could be a very, very expensive oversight.

    I like 24 hour clocks, but there’s no clock configuration. Dropping a buck on 24 Hours solves that problem.

    My old Zire 71 reminded me of my few appointments & things-to-do, but the Fire lacks the whole Android calendar infrastructure. The Calengoo app syncs with my (previously unused) Google Calendar & Contacts, which means that they now know my social network (such as it is) and what I’m up to. So it goes…

    The system volume control exposes only the Media Volume sound channel. Calengoo produces reminders through the Notification sound channel and, under certain perverse conditions that took me about two days to encounter, can mute that channel and leave it muted forever more. The only way to get audible reminders again is by installing a separate mixer app and resetting the levels: Volume Manager Free.

    Hint: to get dependable audible reminders when the Fire is asleep (which is most of the time), you must enable Pop-up Reminders and disable Pop-up windows, because the dialog box occasionally kills the sound. With that configuration, you’ll get a note in the status bar along the top of the display for each reminder. Set the reminder repeat interval to at least a minute to have enough time for password typing…

    The main reason I got a Fire was to carry all my datasheets & manuals in my pocket, hence the need for color and a backlit screen. Although the Fire can handle PDFs without an app, the native interface leaves quite a bit to be desired. Dropping a few bucks on ezPDF Reader solves most of those problems. Choosing a single file from a collection of several hundred, using a selection browser that ignores the overlaid subdirectory structure, remains challenging.

    File Expert helps a bit by presenting subdirectories and their contents. I think that might be the only way to find a specific PDF.

    Engineering bears need an RPN calculator, of which NeoCal Lite seems to be the best of the bunch.

    Passwords go in KeePassDroid, although it has a clunky clipboard interface to other apps. Of course, any Android app can root the Fire and steal my sensitive bits; that seems to not bother anybody else, so why should I worry? The advantage of using a unique password for each website seems to outweigh the disadvantage of having a single password controlling all of them.

    Turn off the browser’s helpful “remember passwords” function, though…

    Although I’m now using Dropbox to back up the KeePassDroid database file, that whole interface seems overly awkward and I’d rather have encryption applied to every Dropbox file.

    Putting the KeePassDroid database file in the Dropbox folder requires a bit of intervention, as KeePassDroid provides no way to specify the database location. You must find the Dropbox folder using File Expert, slow-click the database file, then drill down through File Expert’s menus in order to specify that KeePassDroid should open the file. After that, KeePassDroid will remember its location. For future reference, it’s at:

    /mnt/sdcard/Android/data/com.dropbox.android/files/scratch/keepass.kdb

    The alert reader may wonder why a Kindle Fire, with a conspicuously missing SD Card slot, has an sdcard subdirectory structure hanging from /mnt: that’s just the way it is. I suppose that’s baked into the Android filesystem; hooray for hardware independence and futureproofing.

    The built-in Silk browser runs slower (certainly, no faster) with Accelerate Page Loading turned on, so there seems no compelling reason to sluice my web content through Amazon’s servers. Not that turning it off improves privacy, of course.

    The Maxthon Mobile Web Browser works reasonably well. The highly regarded Dolphin HD browser isn’t available from the Amazon App Store and sideloading apps from Google Play seems unreasonably difficult. The Firefox Aurora browser isn’t quite ready for prime time, but is the only browser to cover its password database with a master password.

    For the occasional times when I need a stopwatch or timer, the aptly named Stopwatch and Timer app should suffice. It has a breathtakingly awkward UI compared to the Zire app, showing that re-invented wheels sometimes sport square corners…

    ColorNote supports both checklists and text notes for my simple needs.

    Sketch-n-Draw ably demonstrates the Fire’s huge latency between touch-pad input and LCD output; it’s impossible to actually draw anything meaningful. FWIW, the ancient Zire had no trouble doing that, adding Yet Another data point to the curve of software demanding more than the hardware can provide.

    The WordPress blogging app is pretty much useless in comparison with their full web interface, not to mention that typing text on the Fire’s one-finger (or, for those with smaller hands, two thumbs) keyboard is agony, not to mention that the Fire lacks a camera, a microphone, and USB host support. It’s a media consumption device, not a media production device; I knew that when I bought it.

    Although it’s awkward, a conductive-tip Acase stylus helps during extended screen-poking sessions. I have my doubts about the rubbery tip’s durability, though.

    All in all, the Fire seems serviceable…

  • Converting DICOM X-ray Images to Something Useful

    For reasons that aren’t relevant here, we have a CD bearing X-rays of Mary’s shoulder. Of course, they’re in DICOM image format and come with a relentlessly Window-centric viewer that won’t run in Wine and can’t export the files in a more useful format.

    Imagemagick to the rescue:

    
    convert /media/floppy/DICOM/997313/00100000 "Mary Shoulder 2.jpg"
    
    
    Mary Shoulder 2 - detail
    Mary Shoulder 2 – detail

    They tell us she has great bones and everything worked out fine…

  • Adobe Flash for Linux: Parting Gift

    Very recently, Youtube videos (including mine) took on a Smurf aspect: blue skin tones and other weird colors. I don’t spend a lot of time watching videos, but I’m pulling together a talk and wanted to be sure my videos still worked.

    Come to find out that:

    • Adobe is dropping Flash for Linux after version 11.2
    • The most recent update swapped the UV color channels
    • Adobe can’t reproduce the problem, hence no fix is in the offing

    At least for Youtube videos, one can turn on their HTML5 video option to avoid Flash, but that doesn’t fix the other issues.

    The recommended FlashVideoReplacer  plugin didn’t work for me in Xubuntu 10.10, alas.

  • Ubuntu 12.04: Random Crashes

    As if that, that, and that weren’t enough, Ubuntu 12.04 suffers from random crashes that occur without doing anything more challenging than turning the damned thing on and signing in to a user account.

    That problem report dates back to mid-December of 2011 and investigation has been ongoing, with notes like:

    We are getting tons of crash reports in Ubuntu (https://launchpad.net/bugs/507062) about programs crashing

    Yet Canonical decided to ship 12.04 anyway, with no fix in sight.

    I think disabling suspend mode reduces the number of random crashes, but it still seems to be about one a day. Resuming from suspend mode definitely messes up the network connection more often than not, so we just won’t suspend it again.

    This was a test installation on the Lenovo Q150, a bone-stock consumer PC, to see if I should upgrade the creaky 10.10 setup on my desktop box. Given the weird collection of hardware on my box (left- and right-hand trackballs, tablet, dual monitors with one rotated to portrait mode, etc), I’d hoped a “Long Term Support” version of Ubuntu / Xubuntu / whatever would be stable enough for use right out of the chute. Given the pervasive nature of the problems with 12.04, it’ll be at least a few more months before the code settles down and starts flying right.

    That’s not encouraging for what was supposed to be a well-tested release, with more attention paid to stability than fancy features.

    Mary is not pleased.

  • Ubuntu 12.04: nVidia Downgrade

    Having installed Ubuntu 12.04 on that Lenovo box, which has an nVidia graphics chip, we find there’s an error somewhere inside the current 295.40 (and perhaps previous versions) of the proprietary nVidia driver that causes random video lockups which generally require rebooting that sucker. Of course, the default Unity desktop requires that driver for 3D operations like compositing, because the Free Software drivers don’t / can’t do 3D in hardware.

    How is it that a (nominally) Open Source / Free Software OS requires proprietary drivers just to present the UI? Oh, right, 3D is glitzy and that’s what matters most in these degenerate days.

    Anyhow.

    The least-likely-to-fail solution seems to be disabling the nVidia driver, which enables the Nouveau driver, which does 2D just fine, which lets Unity stumble along. Reverting to 295.33 seems to work for some folks, but I have other things to do…

  • Ubuntu 12.04: GRUB2 Tweaks

    The default Grub2 video mode for Ubuntu 12.04 is 640×480, which looks rather overwhelming on a 24 inch monitor that can do 1920×1600. I’m also a fan of Old Skool scrolling text, because when something goes wrong it’s handy to get an actual hint in real time.

    Thus, some Grub tweakage was in order:

    GRUB_DEFAULT=saved
    GRUB_SAVEDEFAULT=true
    #GRUB_HIDDEN_TIMEOUT=0
    GRUB_HIDDEN_TIMEOUT_QUIET=true
    GRUB_TIMEOUT=5
    GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
    #GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
    GRUB_CMDLINE_LINUX=""
    
     ... snippage ...
    
    # Uncomment to disable graphical terminal (grub-pc only)
    #GRUB_TERMINAL=console
    
    # The resolution used on graphical terminal
    # note that you can use only modes which your graphic card supports via VBE
    # you can see them in real GRUB with the command `vbeinfo'
    #GRUB_GFXMODE=640x480
    #GRUB_GFXMODE=1600x1200
    GRUB_GFXMODE=1280x1024
    

    AFAICT, it’s impossible to:

    • Page(*) the output of the Grub vbeinfo command. A blind stab at 1600×1200 turned out to be too small and painfully slow at scrolling in graphics mode.
    • Boot a text-mode console in anything other than 80 characters x 24 rows, so un-commenting the GRUB_TERMINAL line isn’t helpful.

    This being Grub2, you must do this special dance (anybody remember when one of Grub’s advantages over Lilo was that it didn’t require a special dance?) to make it work:

    sudo nano /etc/default/grub
     ... make changes & save ...
    sudo update-grub
    sudo reboot ; exit
    

    That’s from an SSH session across the room, of course…

    Incidentally, shutting off the graphic drivel immediately revealed that those NFS mounts weren’t happening because statd wasn’t running. Knowing that immediately would have saved some diagnostic time, yes, it would.

    (*) The Official Grub2 doc suggests set pager=1, but there’s no way to discover that using help set at the Grub2 command line. Now we both know and maybe we’ll remember it for the next time.

  • Ubuntu 12.04: NFS Mounts vs. Upstart

    Back in the old days, the Unix startup sequence was rigidly fixed. For a variety of reasons, that’s no longer the case; Ubuntu (and, presumably, other distros) now use upstart, which turns the startup sequence into a lightly documented Pachinko machine. This parallel processing presumably works great for most of Ubuntu’s use cases and falls flat on its face for me: I’m apparently the only person who expects NFS mounts to be in place before signing in.

    Well, maybe other folks expect that, but the entire startup mechanism is apparently broken as designed.

    The only solution seems to be stalling the user sign-on screen by jamming the display manager until the NFS client hauls itself to its feet. This takes up to a minute, for reasons I do not understand, but it’s better to let it run to completion rather than signing on and expecting one’s files to be in the right places. Email clients, in particular, have difficulty coping with missing files.

    The fix involves adding a line to /etc/init/lightdm.conf, as mentioned there (albeit with incorrect syntax):

    start on ((filesystem
               and runlevel [!06]
               and started dbus
               and (drm-device-added card0 PRIMARY_DEVICE_FOR_DISPLAY=1
                    or stopped udev-fallback-graphics)
               and mounted MOUNTPOINT=/mnt/bulkdata)
              or runlevel PREVLEVEL=S)
    

    I tried to check for another filesystem that should also be mounted, but, as I understand neither the syntax nor the semantics of the language, what you see is what finally worked. As it turns out, upstart's syntax error messages aren’t particularly helpful; a single line (helpfully relating, perhaps, that the parser expected a token on line 16) appears on VT 7, but if you don’t know to switch from VT 1, you’ll never get even that minimal assistance. No, such errors don’t appear in the /var/log/upstart/* logs.

    For unknown reasons, waiting for the remote-filesystems event didn’t delay the startup at all. Evidently, mountall emits that event almost immediately, long before the NFS mounts happen. Perhaps the event occurs even when the mount fails, contrary to what the doc suggests?

    Most of the debugging occurred through an ssh session across the room. Edit the file, try a new version, reboot, watch for the filesystems to come up, watch for the sign-in screen to appear. Or not, as the case may be.

    Grumpy though I may seem, the great thing about Open Source / Free Software is that when it breaks, you have access to all the pieces and can actually fix the problem. That makes up for nearly everything, I’d say.

    No, I didn’t update any of those bug reports or start another one. It’s obvious this isn’t getting any attention, so what’s the point? If you’re also having the problem, you’ll eventually wind up here…

    FWIW, I knew the NFS mounts weren’t working because I always set the screen background to an image on the file server: no mount = no picture = fix-the-problem-now. This image seemed appropriate:

    XB-70A Cockpit
    XB-70A Cockpit

    Back then, transistors were countable resources…

    [Update: The previous picture link, now broken, was to http://www.nasaimages.org/luna/servlet/detail/nasaNAS~2~2~2995~104520. The revised link points to a description on archive.org, with versions of the picture available for download.]