Re: Odd build breakage in 4.9-rc7

From: Jarod Wilson
Date: Fri Dec 02 2016 - 17:41:41 EST


On 2016-12-02 3:11 PM, Nicolas Pitre wrote:
On Thu, 1 Dec 2016, Paul Bolle wrote:

On Thu, 2016-12-01 at 12:42 -0500, Nicolas Pitre wrote:
OK I understand what the problem is. However most of those hunks below
are definitely wrong. ;-)

Probably. By now I've narrowed it down to just these two hunks:

And they're both wrong. ;-) There is no relation between MODVERSIONS and
TRIM_UNUSED_KSYMS.

I'm trying to determine the best way to fix it. Stay tuned.

Will do. I'm curious to see what a proper fix might look like.

Here it is:

----- >8
Subject: kbuild: fix building bzImage with CONFIG_TRIM_UNUSED_KSYMS enabled

When building a specific target such as bzImage, modules aren't normally
built. However if CONFIG_TRIM_UNUSED_KSYMS is enabled, no built modules
means none of the exported symbols are used and therefore they will all
be trimmed away from the final kernel. A subsequent "make modules" will
fail because modpost cannot find the needed symbols for those modules in
the kernel binary.

Let's make sure modules are also built whenever CONFIG_TRIM_UNUSED_KSYMS
is enabled and that the kernel binary is properly rebuilt accordingly.

For my previously failing case, things behave again with this patch. Thanks much!

Tested-by: Jarod Wilson <jarod@xxxxxxxxxx>

--
Jarod Wilson
jarod@xxxxxxxxxx