Debugging dracut on your live EFI System with qemu

Turn on cttyhack in dracut.conf (as of dracut >= 015):

# echo 'cttyhack="yes"' > /etc/dracut.conf.d/cttyhack.conf

Recreate the initramfs:

# dracut -f

Download the qemu EFI BIOS:

# mkdir ~/efiboot
# cd ~/efiboot/
# wget 'http://downloads.sourceforge.net/project/edk2/OVMF/OVMF-X64-r11337-alpha.zip'
# unzip OVMF-X64-r11337-alpha.zip
# mv OVMF.fd bios.bin
# mv CirrusLogic5446.rom vgabios-cirrus.bin

Sync the live system:

# umount /boot/efi
# umount /boot
# sync; echo 3 > /proc/sys/vm/drop_caches; umount /

Start qemu (you can omit "-L ~/efiboot" on a non EFI system):

# qemu-kvm -L ~/efiboot -m 512 -snapshot -hda /dev/sda -serial stdio

Enter the qemu window (you can use <tab> in the second line):

Shell> blk0:
blk0:\> EFI\redhat\grub.efi

Append to the grub kernel command line:

rd.shell rd.break console=ttyS0 rd.ctty=ttyS0

Boot the kernel

Now, you should see the dracut prompt in the terminal, where you started qemu.

dracut Warning: Break before switch_root

Dropping to debug shell.

switch_root:/# 

Warning: Any CTRL-C goes to qemu instead of the dracut shell.

If you don't want this, you can specify "-serial telnet:localhost:55555,server" and "telnet localhost 55555" for the terminal.

After the debugging, remount the boot partitions:

# mount /boot
# mount /boot/efi