From 0763481e9b4f48798dfd837a1efb714287298018 Mon Sep 17 00:00:00 2001 From: Jorijn van der Graaf Date: Sun, 9 Aug 2026 01:25:20 +0200 Subject: [PATCH] README: modem-preserving install via fastboot boot (RAM) + dd Proven 2026-08-09: RAM-booting writes nothing (modemst byte-identical after), so a fresh install that dd's boot_a and userdata from the booted Linux never triggers the ABL's boot-flash NV wipe. Classic flash flow documented as the wiping alternative. Details in journal/modem. Co-Authored-By: Claude Fable 5 --- README.md | 24 +++++++++++++++++++++--- 1 file changed, 21 insertions(+), 3 deletions(-) diff --git a/README.md b/README.md index 7ffc587..99ed58e 100644 --- a/README.md +++ b/README.md @@ -26,9 +26,27 @@ carriers are very welcome. ## Flashing -Download `boot.img` and `fairphone-fp6.img` from the latest release, unlock -the bootloader ([Fairphone's official process](https://support.fairphone.com/hc/en-us/articles/10492476238737)), -then: +Download `boot.img` and `fairphone-fp6.img` from the latest release and unlock +the bootloader ([Fairphone's official process](https://support.fairphone.com/hc/en-us/articles/10492476238737)). + +**Recommended — modem-preserving install** (`fastboot boot` streams the +kernel to RAM without writing; all writes then happen from Linux, which the +bootloader's boot-flash NV-wipe never sees — see the warning below): + +```sh +fastboot boot boot.img +# wait ~60s; the phone comes up on the USB network as 172.16.42.1 +# (fresh devices land in the initramfs debug shell; telnet 172.16.42.1) +# then write both images through Linux, e.g. over the USB network: +ssh user@172.16.42.1 # or the debug shell on virgin devices +# on the phone: fetch/receive the images and +# dd of=/dev/disk/by-partlabel/boot_a for boot.img +# dd of=/dev/disk/by-partlabel/userdata for fairphone-fp6.img +fastboot erase dtbo # one-time, on the next fastboot visit (safe: verified) +``` + +**Classic install** (simpler, but `fastboot flash boot` **zeroes the modem's +NV** — cellular will be dead until you restore your `modemst` backup): ```sh fastboot flash userdata fairphone-fp6.img