stmhal: os.sync() [apparently] doesn't flush FatFS read buffers
My time to ask dumb questions. I created a new file on pyboard's internal flash over USB mass-storage . Expectedly, it didn't show up. I issued sync on Linux side, it didn't show up. I unmounted filesystem, and it still didn't show up. I issues os.sync() on pyboard, and it still didn't show up. I had to reboot pyboard to get hold of it. I'd say, unmounting mass-storage and os.sync() should be 100% enough.
Add ability to set fatfs label & retrieve serial number.
Currently, under ubuntu 14.04 anyways, the internal volume shows up as: /media/dhylands/4421-0003
This PR adds some functions which allow the volume label to be changed. If I put:
import fatfs
fatfs.label('/flash', 'internal')
into boot.py, then the volume will instead show up as /media/dhylands/INTERNAL
Incidently, you can now retrieve the serial numer:
>>> fatfs.serial('/flash')
1143013379
>>> hex(fatfs.serial('/flash'))
'0x44210003'
and we can see that with no label, the serial number formatted as hex is what's used.