The main complication being that you have to reset the device after doing the first set of probing. Some sneaky devices keep a runtime list of changed sectors which isn't saved to flash. For USB device it's easy as you can just reset the port and let the device re-enumerate, but for sata disks and SD cards I don't know if the same thing is possible.

The code I'm using is here: https://git.gnome.org/browse/gnome-multi-writer/tree/src/gmw-probe.c -- I'm happy to relicence to basically whatever if required.

Can you please elaborate what "fake" devices are? Something like the scsi_debug kernel module with a few extra udev properties to make it look like an SD card? Formatting that should work just fine, though. So I'm afraid I don't know what this is all about?

Also, udisks doesn't do anything special on SD cards for formatting, mounting etc, other than advertising an SD card icon for these drives/volumes. Do you have some more details on what you are trying to do and what fails?

Thanks!

Lots of details here: http://blogs.gnome.org/hughsie/

tl;dr: Fake flash is where the drive is much smaller than the size it reports, so for instance a 16GB drive is actually a 2GB drive, and writing to anything past 2BG either goes to /dev/null or wraps around to the first sector. :/

Gahh, URL was meant to be: http://blogs.gnome.org/hughsie/2015/01/28/detecting-fake-flash/

(In reply to Martin Pitt from comment #2)
> Can you please elaborate what "fake" devices are? Something like the
> scsi_debug kernel module with a few extra udev properties to make it look
> like an SD card? Formatting that should work just fine, though. So I'm
> afraid I don't know what this is all about?

http://www.hadess.net/2015/02/another-fake-flash-story.html
http://blogs.gnome.org/hughsie/2015/01/28/detecting-fake-flash/
http://fake-electronics.blogspot.fr/2013/12/fake-samsung-64gb-microsd-card.html
etc.