Using master from today, I noticed that qemux86 core-image-sato only has 150kb of free disk space on it. I'm not sure what the correct amount of free space should be, but I figure at least 10 MB would do.
Sorry for the confusion, I meant core-image-minimal in the first comment, not sato.
I just did a build with master, the rootfs size is 13M with 11M used (according to df -h), du -sh / reports 9.4M, the minimal image is designed to be just that smallest image to show the smallest footprint. So there is no IMAGE_ROOTFS_EXTRA_SPACE defined (you can use that if you need it), it only uses the minimal IMAGE_ROOTFS_SIZE (8M) or 1.3 x the actual size, in this case 9.4M which gives about 13M for the ROOTFS_SIZE. I agree there should be more that 150kb, so I would like to know if you changed minimal at all? What is the size (via df and du) of the rootfs? Is this after first boot? or did you loop mount it?
Ok, so it seems that on first boot dev.tar is created and eats up the 1M of space in etc, also 134K of space is consumed in /dev itself creating all the nodes, so that explains where all the space went. I am really hesitant to increase the space because we want to show as much real world sizing for the minimal image. The target is to get this to under 8M booted.
Use IMAGE_ROOTFS_EXTRA_SPACE to set the desired amount of free space for application for minimal. Minimal is designed to be smallest possibly footprint.