You will need a "flasher" image. I flash the console flavor since I have absolutely no intention of running X windows on the HDMI. In fact I would be perfectly happy if the HDMI was not there at all. The console image fits just fine into 2G of eMMC.
-rw-r----- 1 tom tom 53019200 Nov 2 2015 bone-debian-7.9-console-armhf-2015-10-30-2gb.img.xz -rw-rw-r-- 1 tom tom 53008176 Mar 18 2016 BBB-eMMC-flasher-debian-7.9-console-armhf-2015-10-30-2gb.img.xz -rw-r----- 1 tom tom 436301260 Nov 2 2015 BBB-eMMC-flasher-debian-7.9-lxde-armhf-2015-10-30-2gb.img.xzThe other two images with the word "console" in them are what you want. The one named "bone-debian-*" will boot and run from the SD card. This is not what you want. The other one, named "BBB-eMMC-flasher-debian-7.9-console-armhf-2015-10-30-2gb.img.xz" is what you want. You put this on a micro-SD card, boot it, let it run its course, and it puts debian onto your on board eMMC, annihilating whatever is currently there.
I am providing my copy of this flasher image (see link above) since it has been incredible useful to me and may also help others. I am not seeing 2G console images in the current offerings.
More recent images are available. Not all will fit into 2G eMMC. Be careful to get an image for the BBB and not just a "beaglebone" or "X15" or something. You are on your own. Take care.
Find a micro-SD card someplace (I use an 8G, because that is what I have laying around). Put this into an SD card reader and plug it into your linux desktop. Pay careful attention to what device it mounts up as. It will be something like /dev/sdb or /dev/sdc. Let's say it is /dev/sdc. If your system automounts it, unmount it. Then be darn sure you don't do the following to one of your system disks, or it will be a really bad day for you. In other words, just to be explicit, if you slip up in the following and type sda instead of sdc, your desktop will be history.
su unxz BBB-eMMC-flasher-debian-7.9-console-armhf-2015-10-30-2gb.img.xz dd if=BBB-eMMC-flasher-debian-7.9-console-armhf-2015-10-30-2gb.img of=/dev/sdc
Once you get your power supply ready, insert the compact SD card, hold down the boot button and apply power. It is handy, but not essential to have a serial console hooked up to watch the show. Just watch the LED's as soon as they start moving back and forth you can release the button. Keep your hands off until it powers off (all the lights go out). Mine took about 2 minutes. Add an extra minute because it is booting the kernel and trying to do DHCP before it finally shuts down for good. Remove the flash card and boot it up. With a network cable connected so that it can do DHCP it takes only seconds!!
Debian boots very fast. It also nicely shuts down if you just hold the power button down, maybe for 10 seconds. All the lights go out letting you know it is safe to unplug the unit.
For the record, after the install on a 2G rev B board, the df command shows:
rootfs 1812668 192424 1526500 12% /
The reason (as I understand it) is this. That boot button just tells the onboard boot ROM what device to fetch U-Boot from. Aparently a reset just goes back to U-Boot. You can read more about this here:
Tom's Computer Info / firstname.lastname@example.org