I am using the Occidentalis distro and stupidly ran apt-get upgrade without thinking about the repercussions. After a reboot I now am on a stock kernel, which means I lost kernel support for OneWire, which was my reason for using Occidentalis.
Is there any way for me to undo what I did, short of reimaging the SD card?
You could mount the SD Image under Linux using sudo mount -o loop occidentalis.img /mnt/sd (the directory /mnt/sd must exist.) Then cd to /mnt/sd/boot/ and do sudo cp kernel.img /boot/kernel.img
Reboot and 1-wire support will be enabled.
This may not be necessary however. Newer versions of Raspbian (which you now have as you updated the system) there is a kernel module called w1-gpio. Put this in your /etc/modules. You will also want to add w1-therm if you use a 1 wire temperature sensor such as a DS18x20.
/boot/and the headers in/usr/src/. Show us the output oflsin those two directories? – Jivings Sep 28 '12 at 06:02ls /boot/ && ls /usr/src/and posting the results. That will give us a better chance of giving you an answer. – RPiAwesomeness Mar 23 '14 at 20:01