jhl::mafipulation

Sun, 28 Jul 2013

Virtual maildirs in mutt
I've been using mutt as my primary mail client for years, and it's lovely and fast. One of my persistent bugbears, though, is the lack of ability to dynamically filter and search mail, which most modern mail clients are pretty good at.

If you have an external search tool - like find or notmuch - you can easily produce a Maildir full of symlinks to real messages. But if you change message flags, or try and move or delete messages, the original message is unaffected; only the symlink changes.

Here's a simple script that, given a Maildir of symlinks (all in cur/, please), runs a program for you; after the program has run, it checks for any changes to the mails, corresponding to flag changes or deletion, and them applies them to the original messages.

I use this to view all the emails I have flagged, for example:

#!/bin/sh

MAILDIR="$HOME/mail/"            # path to all your mail
FLAGGED="${MAILDIR}/flagged"     # path to your flagged maildir

set -e

mkdir -p $FLAGGED/{cur,new,tmp} || true
rm -f ${FLAGGED}/cur/* || true

find ${MAILDIR} -regextype posix-extended -regex '.*,[^,]*F[^,]*$' -print0 \
    | xargs -0 ln -s -t ${FLAGGED}/cur

echo -n "flagged messages: "
ls ${FLAGGED}/cur | wc -l

vmutt ${FLAGGED} "mutt -f ${FLAGGED}"

Wed, 03 Jul 2013

Japanese data SIM adventures
I've just arrived in Osaka, and so has my b-mobile Visitor SIM, which promises a prepaid data connection. Unfortunately, my phone doesn't even attempt a data connection, because the SIM won't let the phone register on the network at large - and it just gives up.

I was pretty grumpy at having a non-returnable $30 SIM I can't use. So I booted my phone into baseband mode (where the baseband IC presents itself directly on the phone's USB port, allowing me to send it AT commands). Checking the network registration with AT+CREG yields 3 - registration denied. But the GPRS registration, AT+CGREG, is valid! Evidently not a situation the phone's designers considered. But how do we use it?

The answer is to use the +CGDATA command, which opens a connection we can use for PPP. Now you just need to set up PPP... update: there is a super neat solution by Josua Dietze, check the bottom of this post for the link!

Setting up PPP on Android

I had to build chat and ended up building my own pppd because the Android one logs to the Android logs (duh), so here they are as binaries for you: chat, and pppd. I put them in /system/xbin.

You then need to write the following files: /etc/ppp/options.mobile, changing ttyUSB4 for your tty:

ttyUSB4
modem
passive
novj
defaultroute
noipdefault
usepeerdns
persist
holdoff 10
maxfail 0
noauth
nodetach
debug

/etc/ppp/peers/mobile, changing (or removing) the user/password lines:

file /etc/ppp/options.mobile
user "bmobile@fr"
password "bmobile"
connect "/system/xbin/chat -v -t15 -f /etc/ppp/chat.mobile"

Now for /etc/ppp/chat.mobile, where you must replace bmobile.ne.jp with your APN:

TIMEOUT 10
ABORT 'ERROR'
ABORT 'BUSY'
ABORT 'NO CARRIER'
'' ATZ OK
'AT+CGDCONT=1,"IP","bmobile.ne.jp"' OK
AT+CGDATA="PPP",1 CONNECT

Finally, /etc/ppp/ip-up, which you must then chmod 755:

#!/system/bin/sh

ip route add default via $4
setprop net.dns1 $DNS1
setprop net.dns2 $DNS2

/system/xbin/pppd call mobile

Of course, apps which use the Android network manager to decide if they're connected will still refuse to work - Google Maps won't let you search, for example. Any suggestions for tricking the manager?

The right and obvious answer

Mon, 25 Mar 2013

2013 appears
I've been working on lots of interesting stuff lately, but haven't been working on maintaining my site. I'll be replacing it with a slightly less Web 0.1 vibe in the near future.

Shairport
I've taken over maintainership of Shairport again. Albert Zeyer has maintained it since my initial release in 2011, and I'm very grateful for his work. I'm aiming to slim down the codebase and release a stable, Perl-free 1.0 in the coming months.

Linux on GK802
I've recently wound up with a Zealz GK802 "HDMI dongle", which is a quad-core Freescale ARM SoC jammed into a little stick with USB port on one end and an HDMI output on the other. This is pretty small (and affordable), as powerful Linux PCs go, so I've been heavily involved in the efforts to port Linux to the thing.

So far I've managed to port u-boot, and together with the squad in #imx6-dongle on Freenode IRC, the kernel is looking very healthy too. For more information, check out the project's github page. Support for getting started can be found on IRC.

posted at: 22:34 | path: | permanent link to this entry

Tue, 04 Sep 2012

Drag'n'Derp gets its own site
Tags: cart hardware photos As release nears, the site emerges! Get your latest news from derpcart.com. An RSS feed is provided for your lazywatching pleasure.

posted at: 08:58 | path: /gameboy | permanent link to this entry

Sun, 08 Jul 2012

xfv-4-intel: an Intel .BIO extractor
I recently turned an Intel motherboard into a paperweight by nuking the BIOS ROM, and was disappointed to find that Intel's modern EFI-based BIOSes only support updates from an EFI capsule (the infamous .BIO file). Now, without a clean ROM image to program, the original BIOS is never coming back; but with a little reversing it might be possible to get Coreboot up and running and restore my board to useful status...

Anyway, I found Christoph Pfisterer's xfv tool, which unpacks EFI firmware volumes and capsules. It was missing a couple of features I needed, like decompression of Intel's "custom" compression mode (actually LZMA), so here is a version suitable for dumping Intel BIOS files:

xfv-4-intel.tgz

This makes it trivial to recover irreplaceable pieces like the VGA BIOS, as well as useful information like the static ACPI tables.

posted at: 23:18 | path: /reversing | permanent link to this entry

Sun, 01 Apr 2012

Drag'n'Derp: coming soon to an internet near you!
With the first hand-built carts in the wild for some time now, large-scale release is approaching. There's still a couple of manufacturing issues to sort out, but I'm hoping to offer the first batch of 100 carts in mid-May. Stay tuned for details!

posted at: 06:22 | path: /gameboy | permanent link to this entry

Tue, 08 Nov 2011

Resetting middle-aged Volvo service lights
I recently had to fix my 1996 850's mechanical odometer, and have spent some time reverse engineering some bits and pieces to try and read the mileage out of the instrument cluster electronics. While I haven't managed to figure that out yet, I have picked up a bunch of other codes; and one thing that seems to be quite difficult for this era of Volvo is resetting the service light.

Here's how to do it with an ELM327 or compatible OBD-II interface. You will need a terminal emulator such as minicom (Mac/Linux) or HyperTerminal (Windows). Hit enter after each command. Connect to the port, turn your ignition to II, and make sure linefeeds are on:

> AT L1

> AT RA 13

> AT SH 83 51 15

> AT IIA 51

> AT SI

BUS INIT...OK

> B0 30

> B0 31

AT SI

Mon, 26 Sep 2011

Motorola Atrix: Ubuntu Webtop Construction Kit
Tags: embedded linux android Motorola's Atrix phone has a dual-core Tegra 2 CPU and an HDMI output port, designed for some pretty expensive media and netbook dock accessories. The "lapdock" provides a locked-down browsing environment, based on an old-ish version of Ubuntu, full of crufty binaries. Now that the device is easily unlocked, and alternative Android firmwares are available - such as the excellent CyanogenMOD, in beta form - it's a good time to explore alternative things to run out that HDMI port.

I have built a chroot filesystem based on NVIDIA's last Linux for Tegra release. Unfortunately, LfT has two serious incompatibilities with Android: Xorg hangs, and most binaries (including ls and mount) segfault on startup. The former problem is fairly simple to solve - Xorg hangs after submitting a command buffer to the rendering manager, so it looks like the channel mutex system is incompatible between the Android and Xorg libraries. Cribbing the relevant libraries from the original Webtop filesystem fixes that. Crashing binaries is more puzzling. It turns out that recent Android kernels for Tegra (including that used in the CM7 beta) include a hardware bug workaround that needs corresponding workaround in userspace/libc, or else it crashes. This is worked around by downgrading libc to version 2.12.1, which is not affected. The issue is described in more detail here.

This tarball includes a complete root filesystem. It has no dependency on the original webtop files; you can install it to /osh, or to an SD card partition. It's pretty small (under 200MB), and you'll need to set up your own X environment. A 'go' script is included to mount the needful and chroot from an Android root shell. An advantage of the updated Tegra driver is that you no longer need a crufty binary to change res - use xrandr instead. You will need to issue

xrandr --display DSI-1 --off

Update 26/9/11: I built eglibc 2.13 with

-mtp=soft

Sat, 30 Jul 2011

I'm Not Dead
and so neither is the cartridge project - I've just been really busy. I'm currently assembling resources for batch fabrication. The latest batch of PCBs is AWOL, and I'm waiting on various other things. Nonetheless, aiming to have a batch out around the end of October. Also, adding a firmware feature to support drag'n'drop firmware updates. Stay tuned!

posted at: 02:27 | path: /gameboy | permanent link to this entry

Wed, 11 May 2011

Drag and Drop?
Tags: cart hardware Just to clarify what "drag and drop" means, here's a video of writing a ROM (LSDJ with custom sample kit) and RAM (songs using the kit), at the same time.

Mon, 09 May 2011

Cart Sneak Peek
Tags: cart hardware photos Microelectronic porn!

Yes, that is a micro USB jack on top, so unlike mini-USB carts, the connector actually fits into the case properly...

posted at: 13:59 | path: /gameboy | permanent link to this entry

Drag'n'Derp lives!
Tags: cart hardware So, no update on this for a while; real life has been keeping me busy. Nonetheless, I have found some time recently to get another tranche of work done on the cart design, to the point of having a couple of working prototypes now in testing.

What is it? I'm building a new Gameboy cartridge. Not GBA, not DS, original Gameboy. Why? Because a lot of people still use them, in particular for creating music with software like Johan Kotlinski's LSDj. And to do this, you need a flashable cartridge.

Why? Currently available carts need custom drivers to talk to a computer, and for many types, a cart reader device. This limits their compatibility, and the drivers tend to be poorly maintained after release, too.

Another issue is that all current carts use battery-backed RAM to save user data to - read: music that artists have spent many hours on. These batteries can last ten years in a well-designed system - from the date of manufacture, putting a lifespan on the cartridge and leading to scary reliability issues as they age.

Features:

• 24MBit (3MByte) flash ROM
• 1MBit (128KByte) Ferroelectric RAM
  Instead of battery-backed SRAM, the cart uses F-RAM, which maintains its contents in the absence of power, and has a data retention span on the order of a hundred years.
• USB mass storage emulation
  The cart appears similar to a thumb drive, allowing ROM and RAM contents to be copied via drag and drop. No drivers are required, and supports all USB-capable platforms.

So some prototypes are up, and being tested; this cart is real, and it is coming.
And here's a video of the fabrication of one of the prototypes, courtesy of Tom Gilmore!

Thu, 07 Apr 2011

ShairPort 0.05 released
My girlfriend moved house, and her Airport Express no longer made it with her wireless access point. I figured it'd be easy to find an ApEx emulator - there are several open source apps out there to play to them. However, I was disappointed to find that Apple used a public-key crypto scheme, and there's a private key hiding inside the ApEx. So I took it apart (I still have scars from opening the glued case!), dumped the ROM, and reverse engineered the keys out of it.

So, here is ShairPort, an open-source (Perl/C) replacement.
shairport-0.05.tar.gz
13/4: Updated to 0.05 - cleaner, more informative error handling.
12/4: Updated to 0.04 - compile fixed on non-x86 platforms
11/4: Updated to 0.03 - bugfix release: broken with IPv6 (Mac troubles with iTunes). You must install IO::Socket::INET6 for Perl to fix this - Debian/Ubuntu users, this is lib-io-socket-inet6-perl.

Update: 2013
I'm now maintaining this again. Github repo is here.

posted at: 00:00 | path: /reversing | permanent link to this entry

Fri, 04 Mar 2011

WM8505 state of play - March 2011
The current state of Linux on the WM8505/VT8500 - as available for netbooks and tablets - is as follows:

General stuff

Hardware note

Bento Linux

Linux kernels

VIA's source release

Open source reimplementation

Development discussion takes place on a mailing list (here) - this group is for development discussion, not help requests, please!

Help

Sat, 29 Nov 1969

Mafipulation

• biomedical engineer
• Sydney, Australia
• spare time
• certain person trying to get me to document my work