Hi,

I've found that there's an issue with shutdown minimal linux guest (just 
minimal kernel and initramfs with busybox) via 'poweroff -f' and 'echo o 
 >/proc/sysrq-trigger' and qemu-2.1.0 does not shutdown. I also tried to 
boot the host's kernel+initramfs in qemu, the same result, however on 
bare-metal I can shutdown the whole box with 'poweroff -f'. the 'echo b 
 >/proc/sysrq-trigger' works as well as sending control-alt-delete, the 
guest does reboots.

Worth noting is that I can boot fully featured guest system, like 
Debian7, and shutdown it without any issue on 2.1.0.

After downgrading to 2.0.0 everything works fine.

QEMU-2.1.0 with seabios-1.7.5 have issue.
QEMU-2.0.0 with seabios-1.7.4 works all right.

To reproduce one may want to build a minimal kernel (config attached) 
and use the binary intiramfs image 
https://bitbucket.org/piotrkarbowski/better-initramfs/downloads/release-x86_64-v0.9.tar.bz2

and simply run `qemu-system-x86-64 -kernel bzImage -initrd 
intiramfs.cpio.gz', the initramfs will immediately drop to shell.

-- Piotr.