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Exporting ioctls from out-of-tree module to userspace

DISCUSSION Daniel Hilst Selli 2 participants 3 messages Jul 16, 2014 – Jul 17, 2014

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Daniel Hilst Selli

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#0 lore raw

I write an out-of-tree module and now want to export its ioctls to userspace by installing a header that my modules includes, I was looking for how to do it but can't get it..

I was trying header-y from
https://www.kernel.org/doc/Documentation/kbuild/makefiles.txt but got:
make[1]: *** No rule to make target 'headers_install'. Stop.

Here is what I'm trying: https://gist.github.com/gkos/b0bc4e29a3147b0e6d3b

I see on kernel that usually the exported headers go in include/uapi/SOMETHING and are declared on include/uapi/Kbuild.. but have no idea if this may work for out-of-tree modules, the headers_install exists on linux Makefile so the 'No rule to make target 'headers_install'' doesn't make sense to me ..

I try follow headers_install target on kernel's Makefile but only got frustraded :(

Any idea?

ps: I compiled the module but don't loaded it, so it may have mistakes

Thanks in advance!
Cheers!

#1 lore raw

hi,

in the older kernels (anything before the commit id mentioned below), there is include/Kbuild, where you can do something like this:

header-y += ../../quick-hacks/kernel-modules/mymodule/

and then do a 'make headers_install' from the *source* tree, which seems to do the right thing.

in newer kernels, due to 10b63956fce7f369cc37fd4d994f09bd5203efe4, you need to do the same thing in include/uapi/Kbuild...

kind regards
anupam

Quoted 30 lines · Daniel Hilst Selli

I write an out-of-tree module and now want to export its ioctls to userspace by installing a header that my modules includes, I was looking for how to do it but can't get it..

I was trying header-y from
https://www.kernel.org/doc/Documentation/kbuild/makefiles.txt but got:
make[1]: *** No rule to make target 'headers_install'. Stop.

Here is what I'm trying: https://gist.github.com/gkos/b0bc4e29a3147b0e6d3b

I see on kernel that usually the exported headers go in include/uapi/SOMETHING and are declared on include/uapi/Kbuild.. but have no idea if this may work for out-of-tree modules, the headers_install exists on linux Makefile so the 'No rule to make target 'headers_install'' doesn't make sense to me ..

I try follow headers_install target on kernel's Makefile but only got frustraded :(

Any idea?

ps: I compiled the module but don't loaded it, so it may have mistakes

Thanks in advance!
Cheers!

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#2 lore raw
Quoted 13 lines · Anupam Kapoor

hi,

in the older kernels (anything before the commit id mentioned below), there is include/Kbuild, where you can do something like this:

header-y += ../../quick-hacks/kernel-modules/mymodule/

and then do a 'make headers_install' from the *source* tree, which seems to do the right thing.

in newer kernels, due to 10b63956fce7f369cc37fd4d994f09bd5203efe4, you need to do the same thing in include/uapi/Kbuild...

Quoted 39 lines

kind regards
anupam

Quoted 30 lines · Daniel Hilst Selli

I write an out-of-tree module and now want to export its ioctls to userspace by installing a header that my modules includes, I was looking for how to do it but can't get it..

I was trying header-y from
https://www.kernel.org/doc/Documentation/kbuild/makefiles.txt but got:
make[1]: *** No rule to make target 'headers_install'. Stop.

Here is what I'm trying: https://gist.github.com/gkos/b0bc4e29a3147b0e6d3b

I see on kernel that usually the exported headers go in include/uapi/SOMETHING and are declared on include/uapi/Kbuild.. but have no idea if this may work for out-of-tree modules, the headers_install exists on linux Makefile so the 'No rule to make target 'headers_install'' doesn't make sense to me ..

I try follow headers_install target on kernel's Makefile but only got frustraded :(

Any idea?

ps: I compiled the module but don't loaded it, so it may have mistakes

Thanks in advance!
Cheers!

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Kernelnewbies mailing list
Kernelnewbies at kernelnewbies.org
http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies

Thanks Anupam,

I put the line
header-y += ../../../module/
on include/uapi/Kbuild

But a nasty thing happens... running `make V=1 headers_install' from kernel source gives me this output for my module, which I indented:
http://pastebin.com/Ev6WcsjR

On second line the nasty thing happens, the scripts/headers_install.sh takes two arguments, OUTDIR and SRCDIR. On this line is possible see that both are the same, so the header is installed on where it comes from,

Since I have to patch kernel (include/uapi/Kbuild) to add my uapi header, I can patch kernel to add my module inside tree intead of using out-of-tree modules... Summing up, I'll use sysfs interface which is easier to document and use than ioctl :-) and doesn't need uapi headers...

Thanks again Anupam
Cheers,