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Now Generally Useful: OpenBSD's GPIO Subsystem

Gespeichert von Marc Balmer am Mi., 11/26/2008 - 16:59

OpenBSD has had support for General Purpose Input/Output devices since the 3.6 release. GPIO devices, or gpios for short, provide an easy way to interface electronic circuits which can be as simple as a LED or that provide more complex functionality like a OneWire or I2C bus. The GPIO implementation in OpenBSD 3.6 up to and including 4.4, however, has some problems and drawbacks which made me rework larger parts of this subsystem during the h2k8 hardware hackathon in Coimbra, Portugal.

When seekdir() Won't Seek to the Right Position

Gespeichert von Marc Balmer am Sa., 05/03/2008 - 13:33

The other day, I got an email from Edd, an OpenBSD user, claiming that Samba would crash when serving files off an MS-DOS filesystem. This was Samba built from sources and not the one from ports. Since I use myself Samba a lot and for a quite large user base, I got interested in the issue and started investigating it. What I found out in the end is a surprise and was not expected: A bug that has been there in all BSDs for almost all the time, since the 4.2BSD times or for roughly 25 years...

ldattach(8), a new command to attach line disciplines to a tty

Gespeichert von Marc Balmer am Di., 01/08/2008 - 11:26

Line disciplines have been in Unix since a long time.  While they are not device drivers, they interact with tty devices in a very peculiar manner:  They attach to a tty device and can then look at, or manipulate, the data as it flows through the tty device.  Line disciplines are thus the natural choice when serial data is used in the kernel, e.g. to exchange TCP/IP packets over a serial link using the SLIP protocol or decoding date and time information and provide a timedelta sensor.

Support for the Meinberg Standard Time String: msts(4)

Gespeichert von Marc Balmer am Sa., 01/05/2008 - 13:06

A while ago, Maurice Janssen (maurice@z74.net) sent me a modification of the nmea(4) line discipline to support the Meinberg Standard Time String format. With only a few changes, nmea(4) was turned into the msts(4) line discipline to support Meinberg's serial data format that can be emitted by all their radio clocks. I modified the code a bit, added a manual page, and added the bits needed to attach msts(4) to a tty to the ldattach(8) command. The result is that OpenBSD now has support for virtually any Meinberg radio-clock ever built.

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