Lenovo T99W175 / Foxconn SDX55 update on LVFS breaks FCC unlock

[Thilo-Alexander Ginkel]

Hi,

On Wed, Apr 27, 2022 at 1:50 PM Aleksander Morgado
<aleksander at aleksander.es> wrote:
> > I can boot up Windows and downgrade the firmware, but would be
> > interested in a more permanent fix.
> >
> > What would be needed to figure out the new unlock procedure? Any hints
> > are much appreciated!
>
> Lenovo published already their own FCC unlock tool here
> https://snapcraft.io/lenovo-wwan-dpr
> Haven't tried it yet here though, I'm still using the old SDX55 firmware.
>
> If you don't want to use that closed source tool and If you're
> interested in reverse engineering the process, looking at what that
> tool does would be useful I guess.

IIRC the snap does not support the modem running in an X1E4 that I own
and Iam not sure wthere it implements the old or the new FCC unlock. I
decompiled them some time last year and will have another look later
today. A first look at the Windows drivers using Ghidra didn't reveal
any FCC unlocking functionality, but frankly I am somewhat lost where
to start searching (the Windows drivers are a somewhat bloated set of
.sys files / DLLs).

Thanks,
Thilo