Alpine and frugal installation

Hi there,

I test Alpine for a few weeks and like it.
I'd like to test it more in deep on my work computer (much more powerfull than mines); as I'm not authorized to install software on it, I test distros in frugal mode, booting from GRUB4DOS on a USB stick.

I don't arrive to boot Alpine in this way; all my tests ended with the message

EXT4-fs (sda6): mounted filesystem with ordered data mode. Opts: (null)
failed.
initramfs emergency recovery shell launched. Type 'exit' to continue boot
sh: can't access tty: job control turned off
/ #

Is it not possible to do a frugal installation of Alpine?
I don't find anything about it in the Wiki and on the forum.
(and why Alpine wants to mount sda6 that is the last partition of my HD and on which an other distro is installed?...)