Wipe out eMMC before flashing new OS?

[zetabeta]

Hi,

do I need to wipe out the eMMC before flashing a new OS to it?

In fact, I didn't do it, and after booting from the eMMC lsblk reports, in addition to the expected mmcblk2p1 and mmcblk2p2, two additional entries: mmcblk2boot0 and mmcblk2boot1. I wonder if those are left over from the previous OS...

Many thanks in advance!!

short version: no.

if fromatting means creating partitions and filesystem(s), then not needed.

however, wiping is sometimes good idea, but rather slow. like, sudo dd bs=1M if=/dev/zero of={device} , if paranoid, sudo dd bs=1M if=/dev/urandom of={device} .

if previous o.s. used gpt partition scheme instead of dos, then some partition details are also in the end of the disk (memory card). wiping end and start is good idea. because size varies commans cannot be precise.
coulde be like, sudo dd bs=1M if=/dev/zero of={device} seek=29000 , sudo dd bs=1M if=/dev/zero of={device} count=2 ."skip" and 'seek" taked their reference from "bs". these commands wipe end and start of disk.

- with my first, I immediately ruined the SIM slot because I fell into the infamous use-nano-SIM-with adapter trap ... (I found the warnings against doing that only after I'd ruined it ...)

i use nano to micro adapter, i noticed if not being careful it could damage things. adapters could vary though.