Re: Hot-plugging microSD on Raspberry Pi under FreeBSD

On 2021-Dec-26, at 11:23, bob prohaska <[email protected]> wrote:

> Are there any special protocols to observe when hot-plugging
> microSD cards on Raspberry Pi when FreeBSD is up and running?
> Electrically it's claimed to be ok in this thread by one "jdb":
> https://forums.raspberrypi.com/viewtopic.php?t=281249
> so I'm asking about how the FreeBSD software might react. 
> 
> Obviously filesystems have to be gracefully unmounted, but is
> that all? Can the kernel be "aware" of an unused device and
> get confused if it goes away?

As I remember, for FreeBSD,

A) The built-in microsd card slot works fine for swapping
   media that are not mounted at the time.

but, for example (no mounts involved, RPi4B 8GiByte test context),

B.0) Plug-in the USB reader, no media present. (USB3 example here.)
B.1) Insert a 128 GiByte media to the reader.
B.2) Remove that media.
B.3) Insert a 32 GiByte media to the reader
     (same slot in the reader).

Result:

(da4:umass-sim1:1:0:3): READ(10). CDB: 28 00 0e e2 af ff 00 00 01 00 
(da4:umass-sim1:1:0:3): CAM status: SCSI Status Error
(da4:umass-sim1:1:0:3): SCSI status: Check Condition
(da4:umass-sim1:1:0:3): SCSI sense: ILLEGAL REQUEST asc:21,0 (Logical block address out of range)
(da4:umass-sim1:1:0:3): Error 22, Unretryable error
(da4:umass-sim1:1:0:3): READ(10). CDB: 28 00 0e e2 af ff 00 00 01 00 
(da4:umass-sim1:1:0:3): CAM status: SCSI Status Error
(da4:umass-sim1:1:0:3): SCSI status: Check Condition
(da4:umass-sim1:1:0:3): SCSI sense: ILLEGAL REQUEST asc:21,0 (Logical block address out of range)
(da4:umass-sim1:1:0:3): Error 22, Unretryable error
(da4:umass-sim1:1:0:3): READ(10). CDB: 28 00 0e e2 af c1 00 00 04 00 
(da4:umass-sim1:1:0:3): CAM status: SCSI Status Error
(da4:umass-sim1:1:0:3): SCSI status: Check Condition
(da4:umass-sim1:1:0:3): SCSI sense: ILLEGAL REQUEST asc:21,0 (Logical block address out of range)
(da4:umass-sim1:1:0:3): Error 22, Unretryable error
(da4:umass-sim1:1:0:3): READ(10). CDB: 28 00 0e e2 af fe 00 00 01 00 
(da4:umass-sim1:1:0:3): CAM status: SCSI Status Error
(da4:umass-sim1:1:0:3): SCSI status: Check Condition
(da4:umass-sim1:1:0:3): SCSI sense: ILLEGAL REQUEST asc:21,0 (Logical block address out of range)
(da4:umass-sim1:1:0:3): Error 22, Unretryable error
(da4:umass-sim1:1:0:3): READ(10). CDB: 28 00 0e e2 af ff 00 00 01 00 
(da4:umass-sim1:1:0:3): CAM status: SCSI Status Error
(da4:umass-sim1:1:0:3): SCSI status: Check Condition
(da4:umass-sim1:1:0:3): SCSI sense: ILLEGAL REQUEST asc:21,0 (Logical block address out of range)
(da4:umass-sim1:1:0:3): Error 22, Unretryable error
(da4:umass-sim1:1:0:3): READ(10). CDB: 28 00 0e e2 af fe 00 00 01 00 
(da4:umass-sim1:1:0:3): CAM status: SCSI Status Error
(da4:umass-sim1:1:0:3): SCSI status: Check Condition
(da4:umass-sim1:1:0:3): SCSI sense: ILLEGAL REQUEST asc:21,0 (Logical block address out of range)
(da4:umass-sim1:1:0:3): Error 22, Unretryable error
(da4:umass-sim1:1:0:3): READ(10). CDB: 28 00 0e e2 af ff 00 00 01 00 
(da4:umass-sim1:1:0:3): CAM status: SCSI Status Error
(da4:umass-sim1:1:0:3): SCSI status: Check Condition
(da4:umass-sim1:1:0:3): SCSI sense: ILLEGAL REQUEST asc:21,0 (Logical block address out of range)
(da4:umass-sim1:1:0:3): Error 22, Unretryable error
(da4:umass-sim1:1:0:3): READ(10). CDB: 28 00 0e e2 af ff 00 00 01 00 
(da4:umass-sim1:1:0:3): CAM status: SCSI Status Error
(da4:umass-sim1:1:0:3): SCSI status: Check Condition
(da4:umass-sim1:1:0:3): SCSI sense: ILLEGAL REQUEST asc:21,0 (Logical block address out of range)
(da4:umass-sim1:1:0:3): Error 22, Unretryable error
GEOM_PART: da4 was automatically resized.
  Use `gpart commit da4` to save changes or `gpart undo da4` to revert them.
GEOM_PART: da4 was automatically resized.
  Use `gpart commit da4` to save changes or `gpart undo da4` to revert them.
GEOM_PART: da4 was automatically resized.
  Use `gpart commit da4` to save changes or `gpart undo da4` to revert them.
GEOM_PART: da4 was automatically resized.
  Use `gpart commit da4` to save changes or `gpart undo da4` to revert them.
GEOM_PART: da4 was automatically resized.
  Use `gpart commit da4` to save changes or `gpart undo da4` to revert them.

If you do the 32 GiByte first instead, then for the 128 GiByte you
get notices from GEOM_PART about "was automatically resized"
but it does not "address out of range".

I expect that swapping two media of the same capacity would
be less likely to generate any messages, but that does not
mean that such a swap would be handled fully correctly.

So I unplug the whole reader to swap media. This is messier
if multiple slots are in use (more unmounts and later
remounts).

I expect that this is a FreeBSD issue, not a RPi4B
issue. But I've not tested such under Fedora or the
like or (recently) on a Rock64 or other such.

===
Mark Millard
marklmi at yahoo.com