This should have been fixed by an upstream patch in 5.12
|commit
ed102bf2afed226703eaf85a704755bdbea34583
|Author: Randy Dunlap <rdunlap@infradead.org>
|Date: Thu Apr 15 10:13:52 2021 -0700
|
| um: Fix W=1 missing-include-dirs warnings
|
| Currently when using "W=1" with UML builds, there are over 700 warnings
| cc1: warning: ./arch/um/include/uapi: No such file or directory [-Wmissing-include-dirs]
|
| but arch/um/ does not have include/uapi/ at all, so add that
| subdir and put one Kbuild file into it (since git does not track
| empty subdirs).
Signed-off-by: Christian Lamparter <chunkeey@gmail.com>