> On Jan 25, 2018, at 2:53 AM, i336_ <email address hidden> wrote:
> 
> Hi,
> 
> I've been experiencing various disk I/O issues with Windows NT too, as
> well as with Windows 3.1. I think `-M isapc` may be to blame somehow.
> 
> I've documented my experiences over at
> https://bugs.launchpad.net/qemu/+bug/1745312.
> 
> That report contains information on how to lift out and build the
> before-and-after QEMU commits that I think relate to this being broken.
> John Arbuckle, perhaps you could run through that and see if you
> continue to have issues.
> 
> I was initially going to post that report as a comment in this thread,
> until I realized I was having I/O issues on multiple operating systems.
> 
> -- 
> You received this bug notification because you are subscribed to the bug
> report.
> https://bugs.launchpad.net/bugs/1737194
> 
> Title:
>  Windows NT 4.0 fails to boot from qcow2 installation
> 
> Status in QEMU:
>  New
> 
> Bug description:
>  Windows NT 4.0 will not boot from an installation more than once if
>  installed in a qcow2 image file. A quick fix to this problem is to use
>  the qcow format instead.
> 
>  Steps to reproduce this issue:
> 
>  Create the image file:
>  qemu-img create -f qcow2 winnt4.qcow2 1G
> 
>  Boot from a Windows NT 4.0 Workstation CD:
>  qemu-system-i386 -hda winnt4.qcow2 -cdrom /dev/cdrom -boot d -m 128 -cpu pentium -vga cirrus
> 
>  During the installation process you have the choise between FAT and
>  NTFS. You can pick anyone.
> 
>  After finishing the installation the guest will reboot to install
>  additional items. Once this is done the guest will be bootable. Eject
>  any CD media from QEMU and reboot. You will then see Windows NT 4.0
>  booting up to the desktop. Go to "Start->Shut down" to shut down. Then
>  when Windows is ready quit QEMU.
> 
>  Now try to boot using this command:
>  qemu-system-i386 -hda winnt4.qcow2 -boot c -m 128 -cpu pentium -vga cirrus 
> 
>  The BIOS screen will display an error message:
> 
>  For NTFS: 
>  Booting from Hard Disk...
>  A disk read error occurred.
>  Insert a system diskette and restart
>  the system.
> 
>  For FAT:
>  No bootable device.
> 
>  Additional information:
>  qemu-system-i386 version: 2.10.1
>  qemu-img version: 2.10.92 (v2.11.0-rc4-dirty)
> 
>  If you don't have a Windows NT 4.0 Workstation installation CD, you may download one from here:
>  https://winworldpc.com/product/windows-nt-40/40
> 
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/qemu/+bug/1737194/+subscriptions

I did try to build at commits 306ec6c3cece7004429c79c1ac93d49919f1f1cc and e689f7c668cbd9d08f330e17c3dd3a059c9553d3. Both failed to build on my Mac OS X system. Here is the error message I usually saw: 

  LINK  qemu-io
Undefined symbols for architecture x86_64:
  "_use_rt_clock", referenced from:
      _bdrv_acct_start in block.o
      _bdrv_acct_done in block.o
Undefined symbols for architecture x86_64:
      _qemu_clock_get_ns in qemu-timer.o
  "_use_rt_clock", referenced from:
      _bdrv_acct_start in block.o
      _bdrv_acct_done in block.o
      _qemu_clock_get_ns in qemu-timer.o

In your report you mention using the raw disk image format and VHD(x). I have had great success with the qcow image format. Could you try it and let us know if it fixes things for you?

To create a qcow image file:
 qemu-img create -f qcow <HD image file name>.qcow 1G