Fwd: [robh:dt/next 2/2] fdt_ro.c:undefined reference to `strnlen'

Fwd: [robh:dt/next 2/2] fdt_ro.c:undefined reference to `strnlen'

[Rob Herring]

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With the latest dtc I've imported to the kernel, there is a new
dependency on strnlen. This is giving the ARM decompressor an error. I
have a couple of ideas on how to fix it:

- Move string related functions in dtc to separate file
- Add lib/string.c to the decompressor build
- Build the decompressor with function-sections to discard the string
related functions and avoid the linker error. Also, there's probably a
bit of other unused code that would get dropped. function-sections
doesn't work for the kernel in general, but may for the decompressor.
Nico may know.
- Don't update dtc and take the rest of the day off.

Opinions?

Rob

---------- Forwarded message ----------
From: kbuild test robot <fengguang.wu-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>
Date: Tue, Jan 26, 2016 at 1:33 PM
Subject: [robh:dt/next 2/2] fdt_ro.c:undefined reference to `strnlen'
To: Rob Herring <robh-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
Cc: kbuild-all-JC7UmRfGjtg@public.gmane.org


tree:   https://git.kernel.org/pub/scm/linux/kernel/git/robh/linux dt/next
head:   19b4d23a6157bec049027c435bbbf30e9af07e7f
commit: 19b4d23a6157bec049027c435bbbf30e9af07e7f [2/2] scripts/dtc:
Update to upstream commit b06e55c88b9b
config: arm-at91_dt_defconfig (attached as .config)
reproduce:
        wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross
-O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        git checkout 19b4d23a6157bec049027c435bbbf30e9af07e7f
        # save the attached .config to linux build tree
        make.cross ARCH=arm

All errors (new ones prefixed by >>):

   arch/arm/boot/compressed/fdt_ro.o: In function `fdt_stringlist_count':
>> fdt_ro.c:(.text+0xaf0): undefined reference to `strnlen'
   arch/arm/boot/compressed/fdt_ro.o: In function `fdt_stringlist_search':
   fdt_ro.c:(.text+0xb6c): undefined reference to `strnlen'
   arch/arm/boot/compressed/fdt_ro.o: In function `fdt_stringlist_get':
   fdt_ro.c:(.text+0xc20): undefined reference to `strnlen'

---
0-DAY kernel test infrastructure                Open Source Technology Center
https://lists.01.org/pipermail/kbuild-all                   Intel Corporation

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Re: Fwd: [robh:dt/next 2/2] fdt_ro.c:undefined reference to `strnlen'

[Nicolas Pitre]

On Tue, 26 Jan 2016, Rob Herring wrote:

> With the latest dtc I've imported to the kernel, there is a new
> dependency on strnlen. This is giving the ARM decompressor an error. I
> have a couple of ideas on how to fix it:
> 
> - Move string related functions in dtc to separate file
> - Add lib/string.c to the decompressor build
> - Build the decompressor with function-sections to discard the string
> related functions and avoid the linker error. Also, there's probably a
> bit of other unused code that would get dropped. function-sections
> doesn't work for the kernel in general, but may for the decompressor.
> Nico may know.

Use of function-sections turns out to be more involved than I wish. And 
we've put many special restrictions on the decompressor already. And 
linking dtc (only part of it actually) into the decompressor is only for 
legacy stuff and I'd prefer we don't spend too much time on legacy 
stuff.  Yadda yadda.

So instead I'd simply paste a simple implementation of strnlen into 
arch/arm/boot/compressed/string.c and be done with it.  The one in 
lib/string.c looks dead simple for what it's worth.

> - Don't update dtc and take the rest of the day off.

That is always an option.  Does it really need to be updated?  ;-)


Nicolas

Re: Fwd: [robh:dt/next 2/2] fdt_ro.c:undefined reference to `strnlen'

[David Gibson]

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On Tue, Jan 26, 2016 at 04:52:18PM -0500, Nicolas Pitre wrote:
> On Tue, 26 Jan 2016, Rob Herring wrote:
> 
> > With the latest dtc I've imported to the kernel, there is a new
> > dependency on strnlen. This is giving the ARM decompressor an error. I
> > have a couple of ideas on how to fix it:
> > 
> > - Move string related functions in dtc to separate file
> > - Add lib/string.c to the decompressor build
> > - Build the decompressor with function-sections to discard the string
> > related functions and avoid the linker error. Also, there's probably a
> > bit of other unused code that would get dropped. function-sections
> > doesn't work for the kernel in general, but may for the decompressor.
> > Nico may know.
> 
> Use of function-sections turns out to be more involved than I wish. And 
> we've put many special restrictions on the decompressor already. And 
> linking dtc (only part of it actually) into the decompressor is only for 
> legacy stuff and I'd prefer we don't spend too much time on legacy 
> stuff.  Yadda yadda.
> 
> So instead I'd simply paste a simple implementation of strnlen into 
> arch/arm/boot/compressed/string.c and be done with it.  The one in 
> lib/string.c looks dead simple for what it's worth.

I think that would be my preferred option too.

> 
> > - Don't update dtc and take the rest of the day off.
> 
> That is always an option.  Does it really need to be updated?  ;-)
> 
> 
> Nicolas

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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