uf2 flash partially if not start at 4K boundary

[juju2013]

Trying to do this:

dd if=/dev/urandom of=random.bin bs=1024 count=100
uf2conv.py -b 0x10020100 -o random.uf2 -c -f RP2040 random.bin
cp random.uf2 /mnt/uf2 && sync

Note that address starts at 0x10020100: after reboot, content between 0x****000 and 0x***100 stays unchanged (0xFFFFFFFF), shown as following:
( see https://gist.github.com/juju2013/6e5d129effd3e7d3b43a6bc8973306ff )
$10020100 ........ $10021000 FFFFFFFF $10021100 ........ $10022000 FFFFFFFF $10022100 ........ $10023000 FFFFFFFF $10023100 ........ $10024000 FFFFFFFF $10024100 ........ $10025000 FFFFFFFF $10025100 ........ $10026000 FFFFFFFF $10026100 ........ $10027000 FFFFFFFF $10027100 ........ $10028000 FFFFFFFF $10028100 ........ $10029000 FFFFFFFF $10029100 ........ $1002A000 FFFFFFFF
If that address starts at a 4K boundary, content flashed as expected.

Documentation says ( 2.8.3.2. UF2 Format Details ):
Note that flash is erased a 4K sector at a time, so writing to only a subset of a 4K flash sector will leave the rest of that flash sector undefined. Beyond that there is no requirement that a binary be contiguous.

[kilograham]

Please reformat that output!

[kilograham]

Yes this is a bug. UF2s that do not start on a 4K boundary are not written correctly.
elf2uf2 and the docs will be updated in the next release