[iam-TJ]

I wrote a Linux/BASH tester [0] for this recently that includes instructions on how to create simulated fake devices:

To create simulated (2GiB) fake devices

    fallocate -l 1G fff_test.flash
    DEV=$(losetup --show --find fff_test.flash); echo $DEV
    DEVNUM=$(stat -c %Hr:%Lr $DEV); echo $DEVNUM

With wrap-around sectors:

    dmsetup create --concise "fff_wrap,,,,0 2097152 linear $DEVNUM 0, 2097152 2097152 linear $DEVNUM 0"

With silently dropped writes:

    dmsetup create --concise "fff_drop,,,,0 2097152 linear $DEVNUM 0, 2097152 2097152 zero"

To test:

    fake_flash_finder.bash /dev/mapper/fff_wrap
    Capacity mismatch at LBA 2097152, data wrapped around to block 0. Size is most likely really 1073741824 bytes

    fake_flash_finder.bash /dev/mapper/fff_drop
    Capacity mismatch at LBA 2097152, data does not match what was written. Size is most likely really 1073741824 bytes

To wipe the device if repeating tests:

    dd if=/dev/zero of=/dev/mapper/fff_wrap bs=64M status=progress conv=fdatasync
    dd if=/dev/zero of=/dev/mapper/fff_drop bs=64M status=progress conv=fdatasync

To remove the device:

    dmsetup remove fff_wrap
    dmsetup remove fff_drop
    losetup --detach "$DEV"
    rm fff_test.flash

[0] https://salsa.debian.org/-/snippets/732