Re: [PATCH] staging: vchiq: add 'static' to function definition

[Arnd Bergmann]

On Sat, Oct 22, 2022, at 10:07, Greg Kroah-Hartman wrote:
> On Sat, Oct 22, 2022 at 03:35:48PM +1100, Scott J. Crouch wrote:

> Nice try, but this breaks the build in a very horrible and strange way
> that no one has been able to figure out yet:

I got curious and figured out what happens:

Without CONFIG_OF, of_match_node() always returns NULL, so
vchiq_probe() returns -EINVAL unconditionally before calling
vchiq_platform_init(). 

If vchiq_platform_init() is marked 'static', gcc's dead code
elimination then eliminates it, which in turn means that
'g_fragments_base' is never initialized and gets replaced
with a NULL pointer.

I think the easiest workaround is to take this otherwise correct
patch but at the same time add 'depends on OF' to BCM2835_VCHIQ.
This is a correct dependency as shown by gcc above, and it still
allows compile testing this driver on x86 allmodconfig, which
enables CONFIG_OF.

     Arnd