From time to time, we get wonderful code contributions for ev3dev from other developers. I merge those requests into the main kernel source, and then rebuild the kernel so you don't have to.
These updates are made available at the ev3dev Releases page. The kernel upgrades are normally just uImage files. The are already compressed so gzipping them has very little benefit.
Upgrading your kernel gives you incremental features that are outlined in the descriptive text that goes with each release.
We're assuming that you've got all the steps in the Getting Started section of the wiki going.
Navigate to the ev3dev Releases page and look for the most recent release that's just a uImage file, like this:
Download the uImage file and put it somewhere that your EV3 can see it on an NFS share. Then run these steps:
userid@ev3dev:~$ sudo cp /media/mmc_p1/uImage /media/mmc_p1/uImage.prev
userid@ev3dev:~$ sudo cp nfs/linux/ev3dev-rootfs/uImage /media/mmc_p1/uImageThe first line copies the old uImage kernel file to a safe place on the root of the microSD card. If the new kernel does not boot, then you just need to put the card in your host computer, rename uImage.prev to uImage, and you'll be back where you started.
The second line copies the recently downloaded uImage to the microSD card so that the next time the EV3 reboots, you get the new kernel.
Let's check to see if all the files are where we expect them to be:
userid@ev3dev:~$ ls -al /media/mmc_p1/
total 4781
drwxr-xr-x 2 root root 16384 Jan 5 15:52 .
drwxr-xr-x 3 root root 1024 Dec 29 20:53 ..
-rwxr-xr-x 1 root root 809 Jan 3 2000 ev3dev.rc.local
-rwxr-xr-x 1 root root 2467272 Jan 5 14:28 uImage
-rwxr-xr-x 1 root root 2406432 Dec 29 15:53 uImage.prevYes, they are all there. You can see the newer (and bigger) uImage file, and the old uImage.prev file is there too.
So now, all we need to do is reboot, and we're done...
userid@ev3dev:~$ sudo rebootCongratulations, you have just updated the kernel on your EV3 running ev3dev!