qemu-system-x86_64 does not boot image reliably

Booting image as root user with following command works randomly.

./qemu-system-x86_64 -enable-kvm -curses -smp cpus=4 -m 8192 /root/ructfe2917_g.qcow2

Most of the time it ends up on "800x600 Graphic mode"(been stuck there even for 4 hours before killed), but 1 out of ~20 it boots image correctly(and instantly).

This is visible in v2.5.0 build from sources, v2.5.0 from Ubuntu Xenial and v2.1.2 from Debian Jessie.

The image in question was converted from vmdk using:

qemu-img convert -O qcow2 file.vmdk file.qcow2

The image contains Ubuntu with grub.

I can provide debug logs, but will need guidance how to enable them(and what logs are necessary).

As a side note, it seems that booting is more certain after connecting(or mounting) partition using qemu-nbd/mount.

Please always use the latest version of QEMU (currently v2.10, soon v2.11) when reporting bugs to the upstream QEMU project - we don't support old versions like v2.5 any more. So I guess you wanted to report a bug agains v2.5 in Ubuntu instead and I changed the target of this bug accordingly.

I want a fix ;) and I do expect qemu to get it faster then Ubuntu.
So I set up Ubuntu Zesty(to fullfill dependencies) and build qemu:
QEMU emulator version 2.10.1 (v2.10.1-dirty)
and... it's still there.

Can you tell me how and what logs to provide?

And it still happens on:

QEMU emulator version 2.10.93 (v2.11.0-rc3-dirty)
Copyright (c) 2003-2017 Fabrice Bellard and the QEMU Project developers

This looks not a QEMU bug to me. You may drop "-curses" first, and run again. Once get inside, change grub file(/etc/default/grub) by uncomment GRUB_TERMINAL=console. It should work then. If still not, then blacklist vga16fb and add "fbcon=map:99 text" in grub command line. Remember to run update-grub after change configure file.

Have you ever tried the suggestions from Liang Yan ?

[Expired for QEMU because there has been no activity for 60 days.]