write fails on Linux and FreeBSD

#309 states that:
> Closing issue. DAPLink is OS-agnostic firmware. If there are any bugs that prevent it from working with FreeBSD or any other OS, then we will track and fix the bugs as separate issues.

Here is the issue. I cannot successfully flash micro:bit on FreeBSD and Ubuntu. `mount -o sync` does not help.

#### the micro:bit

```
> cat /mnt/DETAILS.TXT
# DAPLink Firmware - see https://mbed.com/daplink
Unique ID: 9901000052324e45003c8018000000720000000097969901
HIC ID: 97969901
Auto Reset: 1
Automation allowed: 0
Overflow detection: 0
Daplink Mode: Interface
Interface Version: 0253
Bootloader Version: 0243
Git SHA: 64359f5c786363065a41ec15c348e3d53568da03
Local Mods: 0
USB Interfaces: MSD, CDC, HID, WebUSB
Bootloader CRC: 0x32eb3cfd
Interface CRC: 0x53375800
Remount count: 5
URL: https://microbit.org/device/?id=9901&v=0253
```

#### FreeBSD

The `dmesg` on FreeBSD.

```
ugen0.5: at usbus0
umass0 on uhub0
umass0: on usbus0
umass0: SCSI over Bulk-Only; quirks = 0x8100
umass0:1:0: Attached to scbus1
da0 at umass-sim0 bus 0 scbus1 target 0 lun 0
da0: Removable Direct Access SCSI-2 device
da0: Serial Number 9901000052324e45003c8018000000720000000097969901
da0: 1.000MB/s transfers
da0: 64MB (131200 512 byte sectors)
da0: quirks=0x2
umodem0 on uhub0
umodem0: on usbus0
umodem0: data interface 2, has CM over data, has break
ng_ubt: HCI command 0xfc05 timed out
uhid0 on uhub0
uhid0: on usbus0
ng_ubt: HCI command 0xfc05 timed out
```

```
# mount_msdosfs /dev/da0 /mnt
> ls -alh /mnt
total 16
drwxr-xr-x 1 root wheel 1.0K Jan 1 1980 ./
drwxr-xr-x 21 root wheel 1.0K Jul 21 09:18 ../
-r-xr-xr-x 1 root wheel 495B Mar 23 2016 DETAILS.TXT*
-r-xr-xr-x 1 root wheel 284B Mar 23 2016 MICROBIT.HTM*
# cp ~/Downloads/OutOfBoxExperience-v2.hex /mnt
```

In `/var/log/messages`:

```
Jul 22 17:54:02 x270 kernel: g_vfs_done():da0[WRITE(offset=512, length=4096)]error = 6
Jul 22 17:54:02 x270 kernel: g_vfs_done():da0[WRITE(offset=33792, length=4096)]error = 6
Jul 22 17:54:02 x270 kernel: g_vfs_done():da0[WRITE(offset=67072, length=1024)]error = 6
Jul 22 17:54:02 x270 kernel: g_vfs_done():da0[WRITE(offset=1137152, length=12288)]error = 6
Jul 22 17:54:02 x270 kernel: g_vfs_done():da0[READ(offset=512, length=4096)]error = 6
```

from the man page:

```
6 ENXIO Device not configured. Input or output on a special file referred
to a device that did not exist, or made a request beyond the
limits of the device. This error may also occur when, for
example, a tape drive is not online or no disk pack is loaded on
a drive.
```

```
> uname -msr
FreeBSD 13.0-CURRENT amd64
```

#### Linux

```
Jul 22 07:27:01 localhost kernel: [ 52.956967] usb 3-1: new full-speed USB device number 2 using xhci-hcd
Jul 22 07:27:02 localhost kernel: [ 53.106952] usb 3-1: New USB device found, idVendor=0d28, idProduct=0204, bcdDevice=10.00
Jul 22 07:27:02 localhost kernel: [ 53.106964] usb 3-1: New USB device strings: Mfr=1, Product=2, SerialNumber=3
Jul 22 07:27:02 localhost kernel: [ 53.106972] usb 3-1: Product: "BBC micro:bit CMSIS-DAP"
Jul 22 07:27:02 localhost kernel: [ 53.106978] usb 3-1: Manufacturer: ARM
Jul 22 07:27:02 localhost kernel: [ 53.106986] usb 3-1: SerialNumber: 9901000052324e45003c8018000000720000000097969901
Jul 22 07:27:02 localhost kernel: [ 53.234467] usb-storage 3-1:1.0: USB Mass Storage device detected
Jul 22 07:27:02 localhost kernel: [ 53.235039] scsi host0: usb-storage 3-1:1.0
Jul 22 07:27:02 localhost kernel: [ 53.243411] hid-generic 0003:0D28:0204.0001: hiddev96,hidraw0: USB HID v1.00 Device [ARM "BBC micro:bit CMSIS-DAP"] on usb-xhci-hcd.1.auto-1/input3
Jul 22 07:27:02 localhost kernel: [ 53.291396] cdc_acm 3-1:1.1: ttyACM0: USB ACM device
Jul 22 07:27:02 localhost kernel: [ 53.294157] usbcore: registered new interface driver cdc_acm
Jul 22 07:27:02 localhost kernel: [ 53.294166] cdc_acm: USB Abstract Control Model driver for USB modems and ISDN adapters
Jul 22 07:27:02 localhost kernel: [ 53.295470] usbcore: registered new interface driver uas
Jul 22 07:27:03 localhost kernel: [ 54.245484] scsi 0:0:0:0: Direct-Access MBED VFS 0.1 PQ: 0 ANSI: 2
Jul 22 07:27:03 localhost kernel: [ 54.245877] sd 0:0:0:0: Attached scsi generic sg0 type 0
Jul 22 07:27:03 localhost kernel: [ 54.246352] sd 0:0:0:0: [sda] 131200 512-byte logical blocks: (67.2 MB/64.1 MiB)
Jul 22 07:27:03 localhost kernel: [ 54.246919] sd 0:0:0:0: [sda] Write Protect is off
Jul 22 07:27:03 localhost kernel: [ 54.246926] sd 0:0:0:0: [sda] Mode Sense: 03 00 00 00
Jul 22 07:27:03 localhost kernel: [ 54.247918] sd 0:0:0:0: [sda] No Caching mode page found
Jul 22 07:27:03 localhost kernel: [ 54.253295] sd 0:0:0:0: [sda] Assuming drive cache: write through
Jul 22 07:27:03 localhost kernel: [ 54.338963] sda:
Jul 22 07:27:03 localhost kernel: [ 54.340945] sd 0:0:0:0: [sda] Attached SCSI removable disk
```

```
# mount /dev/sda /mnt
# cp /home/trombik/OutOfBoxExperience-v2.hex /mnt/
```

```
Jul 22 07:32:03 localhost kernel: [ 354.666961] VFS: busy inodes on changed media or resized disk sda
Jul 22 07:32:03 localhost kernel: [ 354.679557] sd 0:0:0:0: [sda] tag#0 access beyond end of device
Jul 22 07:32:03 localhost kernel: [ 354.685570] blk_update_request: I/O error, dev sda, sector 131072 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0
Jul 22 07:32:03 localhost kernel: [ 354.696614] sd 0:0:0:0: [sda] tag#0 access beyond end of device
Jul 22 07:32:03 localhost kernel: [ 354.702675] blk_update_request: I/O error, dev sda, sector 131072 op 0x0:(READ) flags 0x0 phys_seg 8 prio class 0
Jul 22 07:32:03 localhost kernel: [ 354.713095] Buffer I/O error on dev sda, logical block 131072, async page read
Jul 22 07:32:03 localhost kernel: [ 354.720348] Buffer I/O error on dev sda, logical block 131073, async page read
Jul 22 07:32:03 localhost kernel: [ 354.727596] Buffer I/O error on dev sda, logical block 131074, async page read
Jul 22 07:32:03 localhost kernel: [ 354.734844] Buffer I/O error on dev sda, logical block 131075, async page read
Jul 22 07:32:03 localhost kernel: [ 354.742091] Buffer I/O error on dev sda, logical block 131076, async page read
Jul 22 07:32:03 localhost kernel: [ 354.749339] Buffer I/O error on dev sda, logical block 131077, async page read
Jul 22 07:32:03 localhost kernel: [ 354.756587] Buffer I/O error on dev sda, logical block 131078, async page read
Jul 22 07:32:03 localhost kernel: [ 354.763834] Buffer I/O error on dev sda, logical block 131079, async page read
Jul 22 07:32:05 localhost kernel: [ 356.805977] VFS: busy inodes on changed media or resized disk sda
Jul 22 07:32:05 localhost kernel: [ 356.806341] sd 0:0:0:0: [sda] 131200 512-byte logical blocks: (67.2 MB/64.1 MiB)
Jul 22 07:32:34 localhost kernel: [ 385.737577] VFS: busy inodes on changed media or resized disk sda
Jul 22 07:32:34 localhost kernel: [ 385.748587] sd 0:0:0:0: [sda] tag#0 access beyond end of device
Jul 22 07:32:34 localhost kernel: [ 385.754568] blk_update_request: I/O error, dev sda, sector 131072 op 0x0:(READ) flags 0x80700 phys_seg 1 prio class 0
Jul 22 07:32:34 localhost kernel: [ 385.765346] sd 0:0:0:0: [sda] tag#0 access beyond end of device
Jul 22 07:32:34 localhost kernel: [ 385.771326] blk_update_request: I/O error, dev sda, sector 131072 op 0x0:(READ) flags 0x0 phys_seg 8 prio class 0
Jul 22 07:32:34 localhost kernel: [ 385.781694] Buffer I/O error on dev sda, logical block 131072, async page read
Jul 22 07:32:34 localhost kernel: [ 385.788951] Buffer I/O error on dev sda, logical block 131073, async page read
Jul 22 07:32:34 localhost kernel: [ 385.796199] Buffer I/O error on dev sda, logical block 131074, async page read
Jul 22 07:32:34 localhost kernel: [ 385.803449] Buffer I/O error on dev sda, logical block 131075, async page read
Jul 22 07:32:34 localhost kernel: [ 385.810696] Buffer I/O error on dev sda, logical block 131076, async page read
Jul 22 07:32:34 localhost kernel: [ 385.817946] Buffer I/O error on dev sda, logical block 131077, async page read
Jul 22 07:32:34 localhost kernel: [ 385.825193] Buffer I/O error on dev sda, logical block 131078, async page read
Jul 22 07:32:34 localhost kernel: [ 385.832442] Buffer I/O error on dev sda, logical block 131079, async page read
Jul 22 07:32:36 localhost kernel: [ 387.846796] VFS: busy inodes on changed media or resized disk sda
Jul 22 07:32:36 localhost kernel: [ 387.847352] sd 0:0:0:0: [sda] 131200 512-byte logical blocks: (67.2 MB/64.1 MiB)

```

```
> cat /etc/lsb-release
DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=20.04
DISTRIB_CODENAME=focal
DISTRIB_DESCRIPTION="Ubuntu 20.04 LTS"

> uname -msr
Linux 5.4.45-sunxi64 aarch64
```

No source file or test is named. Start by reproducing the micro:bit flash failure on Ubuntu and FreeBSD, then trace the DAPLink USB mass-storage write and remount behavior against the kernel errors shown. Done means copying the HEX file completes and the firmware flashes successfully on both operating systems without I/O errors.

Written by the indexing model from the issue text.