Discussion
I wish there was a way to boot into a VM disk image.
Like, OSes have… I dunno, NTFS drivers, so I wish if I had set up an OS in a VM on Windows in a qcow2 image, I could then boot that OS with a FS driver "mount this NTFS drive then mount this qcow2 image within the NTFS drive, then boot off the qcow2 image, then ignore the NTFS drive"
Not sure if I described that clearly
@mcc I'm pretty sure qcow2 would make that impossible, but if it was a raw image instead, it should be doable.
@jernej__s odd. because qcow2 is reusable?
@mcc AFAIK, qcow2 expands dynamically as you write to the (virtual) disk, so you need knowledge of the hosting filesystem.
@jernej__s @bob_zim however if you have a RW NTFS driver, you could apply such knowledge. also i'd expect you need at least a full read driver even with an ISO because the ISO file could be fragmented.
@mcc sounds like the complementary of what a colleague of mine once wanted. Dual boot laptop, they made something on windows (PowerPoint slide so $higherup could add the slide to their deck?) but needed a screenshot of an application from the Linux partition. Rebooting into the other slot was tedious and he would've preferred to boot as a VM.
@pseyfert Parallels could do this. I am pretty sure I did exactly this on a Macbook around 2015 and I am pretty sure I used Parallels
@mcc
I had a feeling windows could do this to some extent? But I'm very much not a windows person. Linux I guess would require horrible initramfs patching and kexec stuff, similar to what ventoy does. I wonder if you could it with iscsi from a server with less nonsense..
@mcc ages ago I did the inverse of this - using a partition for vmware and also booting into said partition. It seems to really confuse OSes when the hardware keeps changing under it.
@mcc you mean use one VM guest to parse out an image that the host then uses to boot another guest from?
@natevw no the reverse, just the computer regular boot into an image file on a drive without repartitioning
@mcc you can do this with linux
@mcc just got an intense flashback to 2008 when you could do this with Ubuntu https://en.wikipedia.org/wiki/Wubi_%28software%29
Wubi (software)