I acquired a Google Nexus 7 (Wi-Fi only) over winter break. I don’t really like getting new devices: they invariably require a lot of work to setup to my liking. Here are some notes:
- Jailbreaking the device from Linux is still fiddly. Ultimately, it’s probably easiest to just find a Windows box and use the Nexus Root Toolkit. The tool is somewhat racy; try the detection code again if it fails the first time.
- Transferring files to/from Linux is a pain in the ass. I have SCP over SSHDroid working; I also tried both DropBear SSH Servers but they did not come with scp binaries and were thus fairly useless for the purpose of file transfer. SSHDroid didn’t work out of the box: I needed to apply comment 14 to make the real scp binaries get picked up in the path. By default, these apps are configured to accept password-authentication (not even keyboard-interactive!) with extremely weak default passwords: make sure you disable that. Still looking for a good rsync implementation. On the USB side, Ubuntu/Gnome/Nautilus natively recognised Nexus in PTP mode but when I tried copying files it hung. MTP is fairly unsupported by Ubuntu 12.10, but go-mtpfs works decently well given a sufficiently modern libmtp. Adam Glasgall has packaged libmtp for Quantal, so go add his PPA, and then follow the installation instructions of go-mtpfs. Update: Transferring files directly to removable media has also worked reasonably well.
- The tablet really does feel like a phone, courtesy of both being on the Android platform. But no 3G means offline is a lot more important, and the larger screen makes certain types of applications a lot more pleasant to use (Update: I’ve settled on MX Player as my video player of choice, since it supports Advanced SubStation Alpha subtitling and MKV files. Unfortunately, it doesn’t support deep color (e.g. 10-bit).)
- Micro USB to USB OTG cable is really handy, esp. for hooking up keyboards or external media. I’d dare say, it’s a more essential accessory than a cover. Note that the micro-USB port isn’t able to power USB devices with high power requirements (e.g. spinning platter external disks), so you’ll need a powered USB hub to connect them. (One symptom of this is if you try to mount an under-powered hard drive, the directory listing will persistently come up empty. It may also may make clicking noises: probably not good for the drive.) I use USB-OTG to perform mounting.
- I tried to get my paper database on Mendeley mirrored onto my tablet, but it’s been pretty tough. I’ve been trying to use Referey, which is a Mendeley-client for Android, but it requires me to somehow propagate my Mendeley SQLite database and all of my PDFs. Dropbox seems like a good match here, except that the official Dropbox client doesn’t support keeping entire folders synced (only favorite files). If you’re like me, and you don’t know exactly what papers you are going to be reading, you have to use something different, e.g. Dropsync. (BTW, if you, like me, have the clever idea of putting the SQLite database with your PDFs, so they all get synced in one folder, don’t ever “Tidy Up”: Mendeley will happily delete your SQLite database as a “foreign object”.) Mendeley and Dropbox seem to interact poorly with each other in various ways (case-sensitivity; also, Mendeley likes to make filenames that are too long, and Dropbox will stupidly and happily accept them).
- The “open windows” button doesn’t appear to properly respect when an application is closed through its own volition (i.e. through an exit button natively supported by the aplication.) This is a bit annoying.
Oh yeah, and Happy New Year. :)
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On the prompting of Steven Hum, I’ve put some finishing touches on my Sup patchset and am “releasing” it to the world (more on what I mean by “release” shortly.) The overall theme of this patchset is that it integrates as much Sup metadata it can with Maildir data. In particular:
- It merges Damien Leone’s sync-back patchset with the latest Sup mainline. The sync-back patchset synchronizes flags such as “Read” or “Trashed” to the Maildir, which can then be propagated back to your IMAP server using OfflineIMAP.
- Furthermore, this patchset has the ability to synchronize arbitrary labels, with a simple set of rules of what folder a message should be moved to depending on what labels it has. For example, inbox and archived messages can be kept in separate folders, so that non-Sup clients can usefully access mail you care about. (Trust me: this is really awesome.) This is coupled with a bonus OfflineIMAP patch which implements fast remote message moving.
- It implements inotify on Maildir, so a full directory scan is no longer necessary to retrieve new messages. The bottleneck for polling is now strictly OfflineIMAP.
- It implements the ability to save sent and draft messages to Maildir, so they show up in third-party clients.
- Finally, it has a number of miscellaneous bugfixes and extra hooks which I have personally found useful.
There is at least a high probability the patchset will work for you, since I’ve been using it actively for a while. Sup will sometimes crash; if it doesn’t happen reproduceably or cause data loss, I probably won’t investigate too hard. Some of my patches are a bit sketchy (especially those labeled HACK: I’ve attempted to document all the skeevy bits in commit messages and code comments.) So, how supported is this version of Sup? Well:
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October has come, and with it, another Ubuntu release (12.10). I finally gave in and reinstalled my system as 64-bit land (so long 32-bit), mostly because graphics were broken on my upgraded system. As far as I could tell, lightdm was dying immediately after starting up, and I couldn’t tell where in my copious configuration I had messed it up. I also started encrypting my home directory.
- All fstab mount entries now show up in Nautilus. The correct fix appears to be not putting these mounts in
/media, /mnt or /home/, and then they won’t be picked up. - Fonts continue to be an exquisite pain in rxvt-unicode. I had to switch from
URxvt.letterSpace: -1 to URxvt.letterSpace: -2 to keep things working, and the fonts still look inexplicably different. (I haven’t figured out why, but the new world order isn’t a complete eyesore so I’ve given up for now.) There’s also a patch which fixes this problem (hat tip this libxft2 bug bug) but I found that at least for DejaVu the letterSpace hack was equivalent. - When you manually suspend your laptop and close the lid too rapidly, Ubuntu also registers the close laptop event, so when you resume, it will re-suspend! Fortunately, this is pretty harmless; if you press the power-button again, it will resume properly. You can also work around this by turning off resume on close lid in your power settings.
- On resume, the network manager applet no longer accurately reflects what network you are connected to (it thinks you’re connected, but doesn’t know to what, or what signal strength it is). It’s mostly harmless but kind of annoying; if anyone’s figured this one out please let me know!
- Hibernate continues not to work, though I haven’t tried too hard to get it working.
- Firefox was being really slow, so I reset it. And then it was fast again. Holy smoke! Worth a try if you’ve found Firefox to be really slow.
- GHC is now 7.4.2, so you’ll need to rebuild. “When do we get our 7.6 shinies!”
My labmates continue to tease me for not switching to Arch. We’ll see…
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(Last IMAP themed post for a while, I promise!)
Well, first off, you’re horribly misinformed: you do not actually want to hack on IMAP. But supposing, for some masochistic reason, you need to dig in the guts of your mail synchronizer and fix a bug or add some features. There are a few useful things to know before you start your journey…
- Read your RFCs. RFC 3501 is the actual specification, while RFC 2683 gives a lot of helpful tips for working around the hairy bits of the many IMAP servers out there in practice. You should also know about the UIDPLUS extension, RFC 4315, which is fairly well supported and makes a client implementor’s life a lot easier.
- IMAP is fortunately a text-based protocol, so you can and should play around with it on the command line. A great tool to use for this is
imtest, which has all sorts of fancy features such as SASL authentication. (Don’t forget to rlwrap it!) Make sure you prefix your commands with an identifier (UID is a valid identifier, so typing UID FETCH ... will not do what you want.) - It is generally a better idea to use UIDs over sequence numbers, since they are more stable, but be careful: as per the specification,
UID prefixed commands never fail, so you will need to check untagged data in the response to see if anything actually happened. (If you have a shitty IMAP library, it may not clear out untagged data between requests, so watch out for stale data!) Oh, and look up UIDVALIDITY. - There exist a lot of software that interfaces with IMAP, all of which has accreted special cases for buggy IMAP servers over the years. It is well worth sourcediving a few to get a sense for what kinds of things you will need to handle.
I am going to share a dirty little secret with you, a secret that only someone who uses and hacks on OfflineIMAP could reasonably know: OfflineIMAP sucks. Of course, you can still use software that sucks (I do all the time), but it’s useful to know what some of its deficiencies are, so that you can decide if you’re willing to put up with the suckage. So why does OfflineIMAP suck?
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As software engineers, we are trained to be a little distrustful of marketing copy like this:
OfflineIMAP is SAFE; it uses an algorithm designed to prevent mail loss at all costs. Because of the design of this algorithm, even programming errors should not result in loss of mail. I am so confident in the algorithm that I use my own personal and work accounts for testing of OfflineIMAP pre-release, development, and beta releases.
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It is once again time for Ubuntu upgrades. I upgraded from Ubuntu Oneiric Ocelot to Ubuntu Precise Pangolin (12.04), which is an LTS release. Very few things broke (hooray!)
- The Monospace font changed to something new, with very wide glyph size. The old font was DejaVuSansMono, which I switched back to.
- Xournal stopped compiling; somehow the linker behavior changed and you need to specify the linker flags manually.
- gnome-keyring isn’t properly starting up for us non-Unity folks. The underlying problem appears to be packaging errors by Gnome, but adding
eval `gnome-keyring-daemon -s to my .xsession` cleared things up. - The battery icon went away! I assume some daemon is failing to get run, but since I have a very nice xmobar display I’m not mourning its loss.
- Default GHC is GHC 7.4.1! Time to rebuild; no Haskell Platform yet. (Note that GHC 7.4.1 doesn’t support the gold linker; this is the
chunk-size error.)
I also upgraded my desktop from the previous LTS Lucid Lynx.
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This is a very quick and easy fix that has made latency on Ubuntu servers I maintain go from three to four seconds to instantaneous. If you’ve noticed that you have high latency on ssh or scp (or even other software like remctl), and you have control over your server, try this on the server: aptitude remove libnss-mdns. It turns out that multicast DNS on Ubuntu has a longstanding bug on Ubuntu where they didn’t correctly tune the timeouts, which results in extremely bad performance on reverse DNS lookups when an IP has no name.
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An “easy”, two-step process:
- Apply this patch for i686. (Why they haven’t fixed this in the trunk, I have no idea.)
- Configure with
CFLAGS="-U_FORTIFY_SOURCE -fno-stack-protector -O2" (this disables fortify source and stack protection which Ubuntu enables by default but interferes with glibc. You need to keep optimizations on, because glibc won’t build without it.) You’ll need to do the usual extra dance of creating a separate build directory and specifying a prefix.
Hope this helps someone else. In case you were wondering why I was building glibc, it’s because I was reporting these two bugs in iconv:
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Things I should be working on: graduate school personal statements.
What I actually spent the last five hours working on: transparent xmobar.
It uses the horrible “grab Pixmap from root X window” hack. You can grab the patch here but I haven’t put in enough effort to actually make this a configurable option; if you just compile that branch, you’ll get an xmobar that is at 100/255 transparency, tinted black. (The algorithm needs a bit of work to generalize over different tints properly; suggestions solicted!) Maybe someone else will cook up a more polished patch. (Someone should also drum up a more complete set of XRender bindings!)
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