https://gcc.gnu.org/bugzilla/show_bug.cgi?id=81863
--- Comment #13 from ard.biesheuvel at linaro dot org --- The kernel does not currently use -mword-relocations. We are looking into it as an alternative to -fpic when building the kernel image as a PIE executable so we can self-relocate at boot time. This allows for randomization of the load offset (KASLR) which is an often requested security feature. The problem with -fpic (and even -fpie) is that the compiler infers from its presence that you are building a shared library which requires preemptible external symbols and should not contain any text relocations. None of these concerns apply to the kernel, and the current workaround is to -include a .h file that sets the visibility 'hidden' pragma, which is a bit tedious. Since we are only interested in absolute references that are runtime relocatable, -mword-relocations seems like the right choice, but it is broken currently on v7 (due to this bug) Ideally, we'd have some logic that takes -ffreestanding into account when deciding how to deal with -fpie/-fpic Also, when generating position independent code for v7 or later, we should probably attempt to use place relative movw/movt pairs rather than relative literals to emit PC relative references.
