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From: Tomek The Messenger <tomekthemessenger@gmail.com>
To: kernelnewbies <kernelnewbies@kernelnewbies.org>
Subject: How to pass flag from makefile to preprocesor when building external kernel module
Date: Fri, 21 Aug 2020 10:01:07 +0200	[thread overview]
Message-ID: <CAA4NGyuL_Hm41YOpojrQUnWUP-n0JpHHxRKfjGsoNx3mYn1gVQ@mail.gmail.com> (raw)


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Hi
I have problem with passing flag from makefile to .c file.
During building external kernel module my macro isn't seen by compiler. I
used plenty of ways.

First way:
ccflags-y += -DMY_FLAG
$(MAKE) -C $(KERNEL_SRC) M=$(SRC)
Second:
$(MAKE) -C $(KERNEL_SRC) M=$(SRC) CFLAGS_my-kernel-module.o="-DMY_FLAG"
Third:
$(MAKE) -C $(KERNEL_SRC) M=$(SRC) CFLAGS="-DMY_FLAG"
Forth:
 $(MAKE) -C $(KERNEL_SRC) M=$(SRC) ccflags-y="-DMY_FLAG"

In general I use bitbake to build external kernel modules.  And I wonder if
bitbake doesn't introduce issue as some of above solution really should
work. And additionally I had to use absolute paths in headers because
relative didn't work so -I append also doesn't work:
SRC := $(shell pwd)
ccflags-y := -I$(SRC)

BR
Tomek

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             reply	other threads:[~2020-08-21  8:02 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-08-21  8:01 Tomek The Messenger [this message]
2020-08-21  8:39 ` How to pass flag from makefile to preprocesor when building external kernel module Tomek The Messenger

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