My Setup: Mac mini with rEFInd installed; Dual boot System: Ubuntu 15.10 and Mac OS X El Capitan;
When I try to boot from an USB-Stick (live disk), which has a Linux distro on it - currently Arch Linux, (Lubuntu before), my system boots directly into Ubuntu on the HDD.
QEMU can boot from the USB-Device (3 Partitions - 1x100M EXT4 with bootflag, 1x4G EXT4 no flag with the system 1x26G FAT32 no flag for files).
Is this an Ubuntu-Issue? rEFInd-Issue? Issue with every Linux system I had on the USB-Stick no matter how I put it on (unetbootin, dd and now installation via QEMU)?