headwind-mdm I am not a member of the GrapheneOS team, and I don't have a Pixel 8. But based on my experience and my reading of the build instructions, it is not clear to me that what you are trying is the best practice.
repo init -u https://github.com/GrapheneOS/platform_manifest.git -b 15-qpr2
I believe this is officially not recommended. The text in the build instructions says "The 15-qpr2 branch of GrapheneOS should be used for generic builds including the emulator, porting to other devices and for non-legacy officially supported devices". The build instructions say "You likely want to use the most recent stable tag, not the development branch, even for developing a feature", and also says "Pick a specific release for a device from the releases page and download the source tree".
So I think it would be better to try something like:
repo init -u https://github.com/GrapheneOS/platform_manifest.git -b refs/tags/2025040700
lunch shiba-cur-eng
It's not clear to me this is recommended. The sole mention of eng that I see on the build page is "We recommend using the sdk_phone64_x86_64 target in either the userdebug or eng variant for most development work". I see no mention of using eng when building for a device.
headwind-mdm For the GrapheneOS 15, the flashing command
fastboot flashall -w
worked perfectly (despite not being mentioned in the official instruction).
For 15-qpr2, it puts my device in a bootloop.
If it isn't recommended and doesn't work, then maybe it's not the thing to do. The flash-all.sh does a lot of things! As just one example, it flashes the bootloader (twice, into two slots), it erases various partitions, and it flashes various partitions in a specific order.
Overall, I think I see three differences between the official build instructions and the steps that are reported to result in a boot loop for you:
- It is recommended to build a tagged (and tested) release, not the branch tip,
- It is recommended to build
user or userdebug, and eng is not mentioned,
- There is no recommendation to use
fastboot flashall -w (the build instructions indicate using generate-release.sh to build a factory image, which I expect will contain a flash-all script).
I don't know what might be going wrong for you, but I would suggest trying exactly the recommended steps before trying changes, which I would recommend be tried one-by-one rather than three at the same time.
Can you report what happens after trying exactly the recommended steps?