Devices with the Exynos 4412


The bootloader of the following devices is incompatible with upstream Linux: When jumping to Linux, the booloader still has: Documentation/arm/booting.rst which is there since 2003 states that:

And upstream Linux won't accept patches to disable the MMU, or the data cache in Linux as they have very good reasons to do that, and they are supposed to be already disabled.

Supporting s-boot

To workaround that we need to: However as the kernel evolved we needed to patch it more and more:

So it's not a viable option in the long run.

Devices with the Exynos 4412

The bootloader of the following devices seems1 to be incompatible with upstream Linux:

However we don't have details yet on what is wrong there (caches, MMU, etc).

1 from #replicant on freenode: <pcercuei> I'm trying to boot a mainline kernel [on the GT-I9100], for some reason it only works if I boot it with u-boot

Longer term options

As u-boot disables the instruction cache in the boot commands before jumping to Linux, we might be able to replace the boot.img by u-boot to workaround the stock bootloader issues.

Having u-boot would also enable many benefits, such as the ability to have Replicant images that run on multiple devices.

As u-boot is capable of running in different ways, when upstreaming the code we will need to make sure that it can run as boot.img but also in other ways depending on the device.

For instance on midas, u-boot can also run with the nonfree and non-redistributable BL1. So it might be interesting to support that as well with the same code because:

We will track the upstreaming status for midas in this bug: #2050