Comment 5 for bug 1776920

I believe I have distilled entire process to few repeatable steps that can be fully reproduced on my Mac. The binary source files - - boot.bin and lzloader.elf - were created on my Linux VM running in VirtualBox on same Mac but I do not think it matters as the execution completely happens on Mac.

The steps executed on my mac:
1. dd if=boot.bin of=image.img > /dev/null 2>&1
2. dd if=lzloader.elf of=image.img conv=notrunc seek=128 > /dev/null 2>&1
3. qemu-img convert image.img -O qcow2 image.qemu
4. qemu-img convert image.qemu -O qcow2 image2.qemu

The end result:
ll image*
-rw-r--r-- 1 *** *** 6684672 Jun 14 17:17 image.img
-rw-r--r-- 1 *** *** 7012352 Jun 14 17:40 image.qemu
-rw-r--r-- 1 *** *** 196616 Jun 14 17:40 image2.qemu

The result of regular compare:
qemu-img compare image.qemu image2.qemu
Images are identical.

The result of strict compare:
qemu-img compare -s image.qemu image2.qemu
Strict mode: Offset 0 block status mismatch!

Images are clearly different.

The same 4 steps executed on my Linux VM behave correctly - image.qemu is TRULY identical with image2.qemu.

Qemu-img on my Mac:
qemu-img --version
qemu-img version 2.12.0
Copyright (c) 2003-2017 Fabrice Bellard and the QEMU Project developers

Details about Mac and OSX version:
Model Name: MacBook Pro
  Model Identifier: MacBookPro13,3
  Processor Name: Intel Core i7
  Processor Speed: 2.7 GHz
  Number of Processors: 1
  Total Number of Cores: 4
  L2 Cache (per Core): 256 KB
  L3 Cache: 8 MB
  Memory: 16 GB

Mac filesystem:
Mount Point: /
  File System: APFS
  Writable: Yes
  Ignore Ownership: No
  BSD Name: disk1s1
  Physical Drive:
  Device Name: APPLE SSD SM0512L
  Media Name: AppleAPFSMedia
  Medium Type: SSD
  Protocol: PCI-Express
  Internal: Yes
  Partition Map Type: Unknown

I am also attaching both source files and images for examination.