20160918

Quick hack: creating a pcDuino3 bootable image from FreeBSD 11.0's BANANA PI image.

Here's a tip about FreeBSD pre-configured armv6 images. For a given SoC, they are all (almost) the same. There's two difference for the Allwinner case (at least for the MP boards): u-boot and the hostname. Recently, I created a u-boot port for pcDuino3 as a slave port. Since I didn't care about the hostname, I thought I'd swap out the u-boot on the BANANA PI image. I snagged it from FreeBSD's download page and installed the u-boot-pcduino3 port. Allwinnner stores u-boot and a small initialization program in the first part of the SD after the MBR partition table. Other SoCs have different boot processes. Currently, you have to check the readme for each one. In the future, there will be a way to insert u-boot into any image.

So, to put the image on the SD card that showed up on my system as /dev/da2:
xz -d < FreeBSD-11.0-RC3-arm-armv6-BANANAPI.img.xz | dd of=/dev/da2 bs=1m
dd if=/usr/local/share/u-boot/u-boot-pcduino/u-boot-sunxi-with-spl.bin of=/dev/da2 bs=1k seek=8 conv=notrunc,sync
This puts the u-boot image (a SPL header which sets up the system to run u-boot coupled with u-boot) onto the disk. You can also uncompress the image you download and insert it there before pushing it out to the SD card. Since I also have a Banana PI I wanted to create an SD card for, I just changed it after it was on the image.

Unfortunately, every board needs a slightly different u-boot image. I have a number of changes I'm testing to help unify the u-boot ports. One of them adds metadata to each u-boot port that a generic imaging tool can use to make things better in the future.


No comments: