Re: Make behaviour changes with new kernel?

[Paul Smith]

Quoting julvr <address@hidden>:

> OK, after some more investigation, it looks like this boils down to whether
> EXTRA_CFLAGS is recursivly expanded or simply expanded...  But again, I'm a
> bit out of my depth in this:  In the kernel, there are several places where
> you see
>
> EXTRA_CFLAGS = xxx
>
> and others where you see
>
> EXTRA_CFLAGS := xxxx
>
> (usb/storage/Makefile and fs/ntfs/Makefile for example)and then a whole lot
> of += modifiers...   So if you have both of these in your make-path, which
> one takes precedence?  If I include a single file that has a :=, does that
> effect all other files, or just sub-makefiles of it?  Does 'export' have any
> effect on this

As best as I recall, and I'm away from my regular system so I don't  
have access to the source ATM, the last one seen takes precedence.

So, in a context where the last assignment was "=", the "+=" is  
interpreted as a recursive expansion.  In a context where the last  
assignment was ":=", the "+=" is interpreted as a simple expansion.   
If there was no prior non-append assignment, the default is recursive  
expansion.

Export has no impact on this.