Date:	Wed, 30 May 2012 12:40:01 -0700
From:	shawn <shawnlandden@...il.com>
To:	Jim Cromie <jim.cromie@...il.com>,
	Russell King <rmk+kernel@....linux.org.uk>
Cc:	Jason Baron <jbaron@...hat.com>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	linux-arm@...r.kernel.org
Subject: Re: include/linux/dynamic_debug.h:111:2: error: implicit
 declaration of function ‘strstr’

summary:

the recently added to arm, CONFIG_KERNEL_XZ is broken because
arch/arm/boot/compressed/decompress.c defines _LINUX_STRING_H
overriding <linux/string.h> used in include/linux/dynamic_debug.h:111


On Wed, 2012-05-30 at 11:53 -0600, Jim Cromie wrote: 
> On Wed, May 30, 2012 at 8:10 AM, shawn <shawnlandden@...il.com> wrote:
> > On Wed, 2012-05-30 at 02:35 -0600, Jim Cromie wrote:
> >> On Tue, May 29, 2012 at 7:43 PM, shawn <shawnlandden@...il.com> wrote:
> >> > jim,
> >> > On Tue, 2012-05-29 at 19:11 -0600, Jim Cromie wrote:
> >> >> On Tue, May 29, 2012 at 5:31 PM, shawn <shawnlandden@...il.com> wrote:
> >> >> >  SHIPPED arch/arm/boot/compressed/lib1funcs.S
> >> >> > In file included from include/linux/kernel.h:23:0,
> >> >> >                 from
> >> >> > arch/arm/boot/compressed/../../../../lib/xz/xz_private.h:15,
> >> >> >                 from
> >> >> > arch/arm/boot/compressed/../../../../lib/decompress_unxz.c:145,
> >> >> >                 from arch/arm/boot/compressed/decompress.c:50:
> >> >> > include/linux/dynamic_debug.h: In function
> >> >> > ‘ddebug_dyndbg_module_param_cb’:
> >> >> > include/linux/dynamic_debug.h:111:2: error: implicit declaration of
> >> >> > function ‘strstr’ [-Werror=implicit-function-declaration]
> >> >> >
> >> >> > git blame shows b48420c1d3019ce8d84fb8e58f4ca86b8e3655b8 as introducing
> >> >> > this call
> >> >>
> >> >> that symbol should have been provided by line 100
> >> >>
> >> >>      98 #else
> >> >>      99
> >> >>     100 #include <linux/string.h>
> >> >>     101 #include <linux/errno.h>
> >> >> ...
> >> >>     108 static inline int ddebug_dyndbg_module_param_cb(char *param, char *val,
> >> >>     109                                                 const char *modname)
> >> >>     110 {
> >> >>     111         if (strstr(param, "dyndbg")) {
> >> >
> >> >> which has:
> >> >>
> >> >>      74 #ifndef __HAVE_ARCH_STRSTR
> >> >>      75 extern char * strstr(const char *, const char *);
> >> >>      76 #endif
> >> >> does your arch have __HAVE_ARCH_STRSTR ?
> >> >> if so, is strstr exported under different conditions ??
> >> > a git grep __HAVE_ARCH_STRSTR did not show and such defines in the arm
> >> > tree
> >>
> >> thats odd - you should have gotten the generic one then.
> >>
> >> >> Can you send me
> >> >> arch/arm/boot/compressed/decompress.i  ?
> >> > I didn't have that file after the failure, but
> >>
> >> nor would you with success, but you did the right thing below..
> >>
> >> > make arch/arm/boot/compressed/decompress.i
> >> >
> >> > summoned it, also including string.o from that folder (which was present
> >> > after the failure)
> >> >
> >> > I am compiling on amd64, using
> >> > export ARCH=arm
> >> > and
> >> > CONFIG_CROSS_COMPILE="arm-linux-gnueabi-"
> >> >
> >> >
> >> > I have had issues with the cross compiler not always being called since
> >> > the 3.5 merge window opened up, (ld reporting corrupted binary files and
> >> > gcc saying it doesn't understand arm-specific flags) and have not yet
> >> > compiled a post-v3.4 successful kernel. This could be a symptom of that.
> >> > (esp as the host arch, x86 DOES have __HAVE_ARCH_STRSTR)
> >> >
> >>
> >> hmm
> >> CONFIG_CROSS_COMPILE is new in 3.5-rc isnt it ?
> >> what happens if you do it the old (3.4) way ?
> > No, CONFIG_CROSS_COMPILE is not new, I've been doing it this way for a
> > few versions, before with the emdebian cross toolchain. in meuconfig it
> > shows up under: General Config --> Cross-compiler tool prefix
> 
> Ah yes - I see its not new (far from it)
> 
> commit 84336466011c589b6af554f2f2f1fcfa1a5c1437
> Author: Roland McGrath <roland@...hat.com>
> Date:   Mon Dec 21 16:24:06 2009 -0800
> 
>     kconfig CROSS_COMPILE option
> 
> 
> > This is the arm toolchain that is in the Ubuntu repos.
> >
> > http://packages.ubuntu.com/precise/gcc-4.6-arm-linux-gnueabi
> 
> I went ahead and installed the arm toolchain from kernel.org,
> and got what look to be errors like you mentioned:
> 
> [jimc@...ucho linux-2.6-dep]$ make
> make[1]: Nothing to be done for `all'.
> make[1]: Nothing to be done for `relocs'.
>   CHK     include/linux/version.h
>   CHK     include/generated/utsrelease.h
>   CC      kernel/bounds.s
> cc1: error: unrecognized command line option '-m64'
> cc1: error: unrecognized command line option '-mno-red-zone'
> cc1: error: unrecognized command line option '-mcmodel=kernel'
> cc1: error: unrecognized command line option '-maccumulate-outgoing-args'
> make[1]: *** [kernel/bounds.s] Error 1
> make: *** [prepare0] Error 2
> 
> this is with toolchain dir in the front of the path, after doing
> make ARCH=arm defconfig
> make xconfig # and adding the cross-compile value
> 
> I got much further when I kept ARCH=arm as make arg;
> it completed the build.  Youre getting it from the environment,
> which should be the same, but its worth a try...
> 
> [jimc@...ucho linux-2.6-dep]$ file vmlinux*
> vmlinux:   ELF 32-bit LSB executable, ARM, version 1, statically
> linked, not stripped
> vmlinux.o: ELF 32-bit LSB relocatable, ARM, version 1, not stripped
> 
> FWIW, this was an in-src build, my attempt at O=../build-arm spat at me.
> 
> 
> > And I have successfully built kernels with this toolchain, and the
> > debian native arm 4.6 compiler, at the same time, using distcc. (however
> > I turned both distcc and ccache off for the error I sent)
> >
> > After having the issues with 3.5, I reinstalled, well parts of the tools
> > chain with apt-get install --reinstall.
> >
> > What is the old way to cross-compile?
> 
> from the config help text:
> 
> Same as running 'make CROSS_COMPILE=prefix-' but stored for
> default make runs in this kernel build directory. You don't
> need to set this unless you want the configured kernel build
> directory to select the cross-compiler automatically.
> 
> FWIW, it sounds more fiddly than using the now-quite-mature
> CROSS_COMPILE config-item
> 
> 
> 
> >> What toolchain are you using ?
> >> can you replicate it using something here ?
> >>
> >> http://kernel.org/pub/tools/crosstool/
> 
> Since I got a build using this, you should give it a go.
> If it works, file a bug report with ubuntu.

arch/arm/boot/compressed/decompress.c

has

#define _LINUX_STRING_H_

which prevents <linux/string.h> from loading


therefore: xz_private.h cannot include <linux/kernel.h>, or
arch/arm/boot/compressed/decompress.c must define strstr

I tried to remove the #include <linux/kernel.h> 
from xz_private.h, and replace it with more specific includes but cannot
because lib/xz/xz_dec_lzma2.c uses min() which is defined in the
<linux/kernel.h> header

  CC      arch/arm/boot/compressed/decompress.o
In file included from include/linux/kernel.h:23:0,
                 from
arch/arm/boot/compressed/../../../../lib/xz/xz_private.h:15,
                 from
arch/arm/boot/compressed/../../../../lib/decompress_unxz.c:145,
                 from arch/arm/boot/compressed/decompress.c:50:
include/linux/dynamic_debug.h: In function
‘ddebug_dyndbg_module_param_cb’:
include/linux/dynamic_debug.h:111:2: error: implicit declaration of
function ‘strstr’ [-Werror=implicit-function-declaration]

> 
> >
> > --
> > -Shawn Landden
> >
> 
> let me know how you get on,
> ( learning from others' pain is one of the values of empathy! )
> 
> Jim


-- 
-Shawn Landden

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