Comment 20 for bug 1797581

Working on this I found by accident that I actually can reproduce:
  VFS: Cannot open root device "squash:http://192.168.122.1:80/squashfs" or unknown-block(0,0): error -6

But the way I got there lets assume some more potential reasons.
I got there by breaking my initramfs :-)

After realizing this I removed the initramfs from the guest definition and got to just the same error.

The reason is that without initramfs the kernel is responsible to handle root= and it has no idea of squashfs.

With that knowledge I re-checked your log at: https://paste.ubuntu.com/p/mkF6Kp4hx8/
It also has no entry like:
  Loading, please wait...
  starting version 237
Which you'd see if systemd in the initrd would take over.
So your bad case also fails to load the initramfs!

That said, why could that be special for just this memory size?

Theories related to the guest size impacting this:
- initrd is placed explicit in PXE config now conflicting with kernel allocations
- initrd is misplaced/misread by PXE code in qemu

@Mike - I'd want to know your exact PXE config
@Mike - It would be great to attach your kernel+initrd+squashfs+rootdisk files to the bug.

Hopefully we can reproduce by providing kernel+initrd via PXE and varying the guest size.