On Fri, 22 Aug 2025 11:58:05 +0200
Christophe Leroy [off-list ref] wrote:

At the time being, TASK_SIZE can be customized by the user via Kconfig
but it is not possible to check all constraints in Kconfig. Impossible
setups are detected at compile time with BUILD_BUG() but that leads
to build failure when setting crazy values. It is not a problem on its
own because the user will usually either use the default value or set
a well thought value. However build robots generate crazy random
configs that lead to build failures, and build robots see it as a
regression every time a patch adds such a constraint.

So instead of failing the build when the custom TASK_SIZE is too
big, just adjust it to the maximum possible value matching the setup.

Several architectures already calculate TASK_SIZE based on other
parameters and options.

In order to do so, move MODULES_VADDR calculation into task_size_32.h
and ensure that:
- On book3s/32, userspace and module area have their own segments (256M)
- On 8xx, userspace has its own full PGDIR entries (4M)

Then TASK_SIZE is garantied to be correct so remove related

                    ^ guaranteed

BUILD_BUG()s.