[Buildroot] Multi-File Kernel Module Build Fails

[Buildroot] Multi-File Kernel Module Build Fails

[Stephen Beckwith]

Greetings,
   I posted this same issue last week and received no response.  After some
more investigation and trying several different options, I am still STUCK
and cannot move forward.
Problem:
 -  if a kernel module has more than 1 source file, Buildroot does NOT pass
in the MAKE_OPTS defined (path for header files).  Compile fails due to
"file not found".

With a single source file, no problems.

In the .mk file:

KMOD_MEM_MODULE_MAKE_OPTS = NETAPP_DIR=$(BR2_EXTERNAL)/netapp

The "Makefile" in the directory:

#inform the kernel that a module needs to be build
obj-m := hwdd_memory.o
hwdd_memory-objs := hwdd_mem.o hwdd_memalgo.o hwdd_cache_algos.o

# Global Includes here
GBL_INCLUDES = $(NETAPP_DIR)/include
KNL_INCLUDES = $(NETAPP_DIR)/include/kernel

#Add here the CFLAGS to pass in to get the Defined Symbol
CFLAGS_hwdd_memory.o := -DCONFIG_NETAPP_HWDD -I$(GBL_INCLUDES)
-I$(KNL_INCLUDES)

Failure:
In file included from
/home/sbeckwith/HBE-1/hwdd/output/build/kmod_mem-0.1.0/./hwdd_memalgo.c:11:0:
/home/sbeckwith/HBE-1/hwdd/output/build/kmod_mem-0.1.0/./hwdd_mem.h:12:26:
fatal error: hwdd_klogger.h: No such file or directory
compilation terminated.

The .mk setup uses:

$(eval $(kernel-module))
$(eval $(generic-package))

Are multi-file inputs NOT supported in this scheme?  These are custom
kernel modules, referencing unique hardware on the target.
Can someone please verify that multi-file kernel modules work using this
setup?

Thanks!
Stephen
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[Buildroot] Multi-File Kernel Module Build Fails

[Thomas Petazzoni]

Hello,

On Tue, 26 Apr 2016 14:44:28 -0400, Stephen Beckwith wrote:

>    I posted this same issue last week and received no response.  After some
> more investigation and trying several different options, I am still STUCK
> and cannot move forward.

Since you didn't post your entire code, we're not able to reproduce the
exact same situation. However, to show how things can work, I've
created a minimal example of a kernel module with two C files and one
header file (to mimic your use case) and then the corresponding
Buildroot package.

See:

  http://thomas.enix.org/example-kernel-module.html

for all the files, both the kernel module itself and the Buildroot
packaging.

Let me know if that works for you.

Best regards,

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

[Buildroot] Multi-File Kernel Module Build Fails

[Thomas Petazzoni]

Hello,

(Resending with the Buildroot mailing list in Cc. Please always keep
the list in Cc. Thanks!)

On Tue, 26 Apr 2016 16:20:17 -0400, Stephen Beckwith wrote:

> KMOD_MEM_MODULE_MAKE_OPTS = NETAPP_DIR=$(BR2_EXTERNAL)/netapp

Get rid of this.

> #inform the kernel that a module needs to be build
> obj-m := hwdd_memory.o
> hwdd_memory-objs := hwdd_mem.o hwdd_memalgo.o hwdd_cache_algos.o
> 
> # Global Includes here
> GBL_INCLUDES = $(NETAPP_DIR)/include
> KNL_INCLUDES = $(NETAPP_DIR)/include/kernel

And those two variable definitions.

> #Add here the CFLAGS to pass in to get the Defined Symbol
> CFLAGS_hwdd_memory.o := -DCONFIG_NETAPP_HWDD -I$(GBL_INCLUDES)
> -I$(KNL_INCLUDES)

And replace this by:

ccflags-y := -DCONFIG_NETAPP_HWDD -I$(src)/include -I$(src)/include/kernel

Again, I've spent time creating an example that I've tested. Since I
can't reproduce your test case, please try my example, which you can
test as I'm providing the entire source code :)

Best regards,

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com

[Buildroot] Multi-File Kernel Module Build Fails

[Stephen Beckwith]

Hi Thomas,
   The MAKE_OPTS and 2 variables are necessary, as the include directory
does NOT get copied into the output/build directory.  I see what you did,
using $(src) - but that's not where the includes are.
   I have ~ 40 modules/drivers/apps that reference these includes, they are
common across these various software components.
   Your suggestion failed, due to the includes not being:
-DCONFIG_NETAPP_HWDD -I/home/sbeckwith/HBE-1/hwdd/
*output/build/kmod_mem-0.1.0*/./include
-I/home/sbeckwith/HBE-1/hwdd/output/build/kmod_mem-0.1.0/./include/kernel

Again, IF I have a single source file module, the setup I have works
perfectly, the include directory outside of the output/build tree gets
referenced and the build is OK.  Only when I have more than one source file
involved does build root not seem to pass the MAKE_OPTS through.

Question:
  -  is it allowed in buildroot to access common include header files
outside of the build directory?  Or should these be somehow copied (via
rsync) as a separate config like item?

Regards,
Stephen

On Tue, Apr 26, 2016 at 4:25 PM, Thomas Petazzoni <
thomas.petazzoni@free-electrons.com> wrote:

> Hello,
>
> (Resending with the Buildroot mailing list in Cc. Please always keep
> the list in Cc. Thanks!)
>
> On Tue, 26 Apr 2016 16:20:17 -0400, Stephen Beckwith wrote:
>
> > KMOD_MEM_MODULE_MAKE_OPTS = NETAPP_DIR=$(BR2_EXTERNAL)/netapp
>
> Get rid of this.
>
> > #inform the kernel that a module needs to be build
> > obj-m := hwdd_memory.o
> > hwdd_memory-objs := hwdd_mem.o hwdd_memalgo.o hwdd_cache_algos.o
> >
> > # Global Includes here
> > GBL_INCLUDES = $(NETAPP_DIR)/include
> > KNL_INCLUDES = $(NETAPP_DIR)/include/kernel
>
> And those two variable definitions.
>
> > #Add here the CFLAGS to pass in to get the Defined Symbol
> > CFLAGS_hwdd_memory.o := -DCONFIG_NETAPP_HWDD -I$(GBL_INCLUDES)
> > -I$(KNL_INCLUDES)
>
> And replace this by:
>
> ccflags-y := -DCONFIG_NETAPP_HWDD -I$(src)/include -I$(src)/include/kernel
>
> Again, I've spent time creating an example that I've tested. Since I
> can't reproduce your test case, please try my example, which you can
> test as I'm providing the entire source code :)
>
> Best regards,
>
> Thomas
> --
> Thomas Petazzoni, CTO, Free Electrons
> Embedded Linux, Kernel and Android engineering
> http://free-electrons.com
>
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[Buildroot] Multi-File Kernel Module Build Fails

[Stephen Beckwith]

Hi Thomas,
   Problem is now solved!  Thank you for your hints, they helped me push
this boulder over the hill.
Regards,
Stephen Beckwith


On Tue, Apr 26, 2016 at 5:00 PM, Stephen Beckwith <embeddedsteve@gmail.com>
wrote:

> Hi Thomas,
>    The MAKE_OPTS and 2 variables are necessary, as the include directory
> does NOT get copied into the output/build directory.  I see what you did,
> using $(src) - but that's not where the includes are.
>    I have ~ 40 modules/drivers/apps that reference these includes, they
> are common across these various software components.
>    Your suggestion failed, due to the includes not being:
> -DCONFIG_NETAPP_HWDD -I/home/sbeckwith/HBE-1/hwdd/
> *output/build/kmod_mem-0.1.0*/./include
> -I/home/sbeckwith/HBE-1/hwdd/output/build/kmod_mem-0.1.0/./include/kernel
>
> Again, IF I have a single source file module, the setup I have works
> perfectly, the include directory outside of the output/build tree gets
> referenced and the build is OK.  Only when I have more than one source file
> involved does build root not seem to pass the MAKE_OPTS through.
>
> Question:
>   -  is it allowed in buildroot to access common include header files
> outside of the build directory?  Or should these be somehow copied (via
> rsync) as a separate config like item?
>
> Regards,
> Stephen
>
> On Tue, Apr 26, 2016 at 4:25 PM, Thomas Petazzoni <
> thomas.petazzoni at free-electrons.com> wrote:
>
>> Hello,
>>
>> (Resending with the Buildroot mailing list in Cc. Please always keep
>> the list in Cc. Thanks!)
>>
>> On Tue, 26 Apr 2016 16:20:17 -0400, Stephen Beckwith wrote:
>>
>> > KMOD_MEM_MODULE_MAKE_OPTS = NETAPP_DIR=$(BR2_EXTERNAL)/netapp
>>
>> Get rid of this.
>>
>> > #inform the kernel that a module needs to be build
>> > obj-m := hwdd_memory.o
>> > hwdd_memory-objs := hwdd_mem.o hwdd_memalgo.o hwdd_cache_algos.o
>> >
>> > # Global Includes here
>> > GBL_INCLUDES = $(NETAPP_DIR)/include
>> > KNL_INCLUDES = $(NETAPP_DIR)/include/kernel
>>
>> And those two variable definitions.
>>
>> > #Add here the CFLAGS to pass in to get the Defined Symbol
>> > CFLAGS_hwdd_memory.o := -DCONFIG_NETAPP_HWDD -I$(GBL_INCLUDES)
>> > -I$(KNL_INCLUDES)
>>
>> And replace this by:
>>
>> ccflags-y := -DCONFIG_NETAPP_HWDD -I$(src)/include -I$(src)/include/kernel
>>
>> Again, I've spent time creating an example that I've tested. Since I
>> can't reproduce your test case, please try my example, which you can
>> test as I'm providing the entire source code :)
>>
>> Best regards,
>>
>> Thomas
>> --
>> Thomas Petazzoni, CTO, Free Electrons
>> Embedded Linux, Kernel and Android engineering
>> http://free-electrons.com
>>
>
>
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[Buildroot] Multi-File Kernel Module Build Fails

[Peter Korsgaard]

>>>>> "Thomas" == Thomas Petazzoni <thomas.petazzoni@free-electrons.com> writes:

 > Hello,
 > On Tue, 26 Apr 2016 14:44:28 -0400, Stephen Beckwith wrote:

 >> I posted this same issue last week and received no response.  After some
 >> more investigation and trying several different options, I am still STUCK
 >> and cannot move forward.

 > Since you didn't post your entire code, we're not able to reproduce the
 > exact same situation. However, to show how things can work, I've
 > created a minimal example of a kernel module with two C files and one
 > header file (to mimic your use case) and then the corresponding
 > Buildroot package.

 > See:

 >   http://thomas.enix.org/example-kernel-module.html

 > for all the files, both the kernel module itself and the Buildroot
 > packaging.

Nice! Notice that the browser ate the <> in your include statements of
mymod-test1.c. I believe you need to use &gt; / &lt; even within <pre>
tags.

-- 
Bye, Peter Korsgaard

[Buildroot] Multi-File Kernel Module Build Fails

[Thomas Petazzoni]

Hello,

On Thu, 28 Apr 2016 21:23:00 +0200, Peter Korsgaard wrote:

> Nice! Notice that the browser ate the <> in your include statements of
> mymod-test1.c. I believe you need to use &gt; / &lt; even within <pre>
> tags.

Fixed, thanks!

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux, Kernel and Android engineering
http://free-electrons.com