Disrecommend RW_LEGACY

[ninelore]

• RW_LEGACY should only be used for dual booting with ChromeOS, otherwise there is a risk of lockout on GSC reboot.
• Recommend submarine instead

[sadlerm4]

Perhaps we can add documentation on enabling the GBB flag so that it won't matter even if enable_dev_altfw is reset.

[ninelore]

Submarine should be the primary recommendation because iirc RW_LEGACY causes bugs in Linux that arent easily solved. @ellyq or @MrChromebox might be able to elaborate further or correct me.

[WeirdTreeThing]

And what does submarine do differently to fix these issues?

[ninelore]

And what does submarine do differently to fix these issues?

Made this issue because of #217 (comment). I don't want to rule out that I misremember that part. Pinged these people for clarification for that reason.

[WeirdTreeThing]

By that logic, we shouldn't recommend submarine because if you wipe ChromeOS and dev_boot_signed_only gets cleared then you are locked out.

[WeirdTreeThing]

In both cases you can use recomod to fix the nvram flags being reset. I'm also not sure how they would reset unless you intentionally did it.

[ninelore]

I'm also not sure how they would reset unless you intentionally did it.

dead battery / GSC reboot?

[WeirdTreeThing]

Google fixed the dead battery thing ages ago. And I've never heard of GSC reboot causing nvram to be wiped. Do you have anything to show these will cause nvram to be lost?

[ninelore]

Mind specifying "ages"? I don't think MrChromebox would write that without reason.

[WeirdTreeThing]

https://www.chromium.org/chromium-os/developer-library/reference/development/developer-information-for-chrome-os-devices/workaround-for-battery-discharge-in-dev-mode/#impacted-devices

[MrChromebox]

I certainly remember post-Haswell/Baytrail devices having the dev_boot_legacy/altfw crossystem flags cleared and users ending up in a situation where they couldn't boot

[WeirdTreeThing]

We already don't recommend RW_LEGACY on EOL devices, so as long as this issue doesn't affect anything still supported I don't think it should matter. And as I said above, submarine would have the exact same issue.

[MrChromebox]

I honestly don't care either way. I'd be happy to drop RWL support entirely

[ninelore]

Is that due to maintenance effort of the RWL images? That'd be one issue submarine could solve. But dropping RWL support is a question whether we want to screw Dual-boot users.

[MrChromebox]

combination of:

• getting edk2 to boot as RWL without ability to debug via serial
• no NVRAM
• issues with i2c devices in stock google firmware
• and other misc issues