I'm trying to just boot the TWRP image for my OnePlus 5t to then install a custom ROM. So I typed fastboot boot "C:\Users\Elias\Downloads\twrp-3.3.1-0-dumpling.img" and it seemed to work and I got the output:

Downloading 'boot.img'                             OKAY [  0.808s]
booting                                            OKAY [ 10.119s]
Finished. Total time: 10.992s

But the device just shows the text: "Fastboot Mode" and doesn't do anything. I now read on this forum that they somehow removed it but it would still be possible with: fastboot -c "lge.kcal=0|0|0|x" boot customrecovery.img but this flag doesn't seem to exist.

The output is:

C:\platform-tools\fastboot.exe: unknown option -- c

My goal is just to install a custom ROM without actually flashing anything except the ROM. So if somebody knows a different way, it would be welcome as well.


There are different versions of fastboot.exe available.

One old version I have has the command line option -c as

-c <cmdline>               override kernel commandline

The recent versions for Android SDK (v29.0.5-5949299) does not has the -c option. Instead it has the option --cmdline which seem to the the exactly same thing:

--cmdline CMDLINE          Override kernel command line.

Therefore you may succeed changing the command-line to

fastboot --cmdline "lge.kcal=0|0|0|x" boot customrecovery.img
  • the command works but sadly now I'm again just getting to the logo screen (the text saying fastboot mode), any idea? – Elias Nov 24 '19 at 12:49
  • @Elias Have you tried the older versions? Also have you read the XDA support thread on TWRP for the OnePlus 5T? forum.xda-developers.com/oneplus-5t/development/… – Robert Nov 24 '19 at 12:58
  • I've skipped through the thread and, correct me if I'm wrong, something about decrypting the data is not working? I'm now trying out a few older builds and see if I get one to work. Do you know if there is any log I could check? So I know what the problem actually is? Also, do you know what --cmdline "lge.kcal=0|0|0|x" does? maybe post a refference link? would be really nice of you :) – Elias Nov 24 '19 at 13:26
  • I have now tried the versions: 3.3.0-0, 3.2.3-1 and, the latest 3.3.1-0 which are all not working. – Elias Nov 24 '19 at 13:33
  • @Elias Using the kernel command line you can pass options to specific drivers. lge.kcal seems to be a part of the display driver system. Depending on the boot progress and the recovery it may be possible that you can get boot messages via adb. – Robert Nov 24 '19 at 13:47

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