[KJ] janitor project: fix gcc 4 warnings

[KJ] janitor project: fix gcc 4 warnings

[Andi Kleen]

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Here's a proposed janitor project if anybody is interested:

The current gcc 4.0 snapshots include some more warnings in -Wall
and changed some existing ones which makes a kernel compilation quite noisy. 

The project would be to fix all these warnings.

Short howto: 

Get
ftp://gcc.gnu.org/pub/gcc/snapshots/4.0-20041219/gcc-core-4.0-20041219.tar.bz2

Untar it and compile with 

mkdir obj
../gcc-*/configure --disable-checking --enable-languages=c --prefix=/usr/local/gcc4
make bootstrap
<as root> 
make install


Then compile an uptodate 2.6 kernel with:

make allmodconfig
make CC=/usr/local/gcc4/bin/gcc 2>&1 | tee LOG
grep warning LOG 

You'll see lots of warnings in LOG. Fix them all and submit patches
through the usual janitor channels.

-Andi


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Re: [KJ] janitor project: fix gcc 4 warnings

[Matthew Wilcox]

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On Sun, Dec 19, 2004 at 08:09:03PM +0100, Andi Kleen wrote:
> Here's a proposed janitor project if anybody is interested:
> 
> The current gcc 4.0 snapshots include some more warnings in -Wall
> and changed some existing ones which makes a kernel compilation quite noisy. 

I think it would get more takers if people didn't have to compile a new
gcc.  If we had a list of -W... flags in older gccs that could simulate
90% of the warnings, this would make it possible for more people to work
on it.

-- 
"Next the statesmen will invent cheap lies, putting the blame upon 
the nation that is attacked, and every man will be glad of those
conscience-soothing falsities, and will diligently study them, and refuse
to examine any refutations of them; and thus he will by and by convince 
himself that the war is just, and will thank God for the better sleep 
he enjoys after this process of grotesque self-deception." -- Mark Twain

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Re: [KJ] janitor project: fix gcc 4 warnings

[Andi Kleen]

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On Sun, Dec 19, 2004 at 07:47:59PM +0000, Matthew Wilcox wrote:
> On Sun, Dec 19, 2004 at 08:09:03PM +0100, Andi Kleen wrote:
> > Here's a proposed janitor project if anybody is interested:
> > 
> > The current gcc 4.0 snapshots include some more warnings in -Wall
> > and changed some existing ones which makes a kernel compilation quite noisy. 
> 
> I think it would get more takers if people didn't have to compile a new
> gcc.  If we had a list of -W... flags in older gccs that could simulate
> 90% of the warnings, this would make it possible for more people to work
> on it.

Problem is that some of the warnings are completely new in gcc 4 and
cannot be enabled with options in older versions. Also with a reasonable
modern machine (Athlon or P4) it won't take that long to do the gcc
compilation.

-Andi

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Re: [KJ] janitor project: fix gcc 4 warnings

[Tobias Klauser]

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Hi

On Sunday 19 December 2004 20:09, Andi Kleen wrote:
> Short howto:
>
> Get
> ftp://gcc.gnu.org/pub/gcc/snapshots/4.0-20041219/gcc-core-4.0-20041219.tar.
>bz2
>
> Untar it and compile with
>
> mkdir obj
> ../gcc-*/configure --disable-checking --enable-languages=c
> --prefix=/usr/local/gcc4 make bootstrap
> <as root>
> make install
>
>
> Then compile an uptodate 2.6 kernel with:
>
> make allmodconfig
> make CC=/usr/local/gcc4/bin/gcc 2>&1 | tee LOG
> grep warning LOG
Cool howto, thanks. Maybe that should go onto the TODO list over at 
kerneljanitors.org?

>
> You'll see lots of warnings in LOG. Fix them all and submit patches
> through the usual janitor channels.

I already compiled GCC4 and it took about 15 minutes on an Athlon Tbird 1.4 
GHz to finish. When compiling Linux 2.6.10-rc3 with GCC4 there are lots of 
warnings (as expected) and even a fatal error.
So I'm trying to fix some of these warnings. They are all over the kernel tree 
and so I'm curious what would be the best method to split and submit the 
patches?

Thanks, Tobias

-- 
Tobias Klauser <tklauser@nuerscht.ch>

GPG-Key 0x3A445520 http://tklauser.politux.org/tklauser.asc
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Re: [KJ] janitor project: fix gcc 4 warnings

[Adrian Bunk]

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On Sun, Dec 19, 2004 at 08:09:03PM +0100, Andi Kleen wrote:
> 
> Here's a proposed janitor project if anybody is interested:
> 
> The current gcc 4.0 snapshots include some more warnings in -Wall
> and changed some existing ones which makes a kernel compilation quite noisy. 
> 
> The project would be to fix all these warnings.
>...
> You'll see lots of warnings in LOG. Fix them all and submit patches
> through the usual janitor channels.

What kind of new warnings does gcc 4.0 emit?

It should be checked whether the warnings are valid and should really be 
fixed.

A past example are the signed warnings pre-releases of gcc 3.3 
(including the pre-release a stable SuSE release shipped as compiler...) 
emitted with -Wall that were no longer emitted in the final gcc 3.3 
release.

Altogether, new warnings in gcc 4.0 might be a nice diagnostics for the 
people who are also trying to find bugs using -W, but I don't see urgent 
reasons for fixing them before gcc 4.0 is actually released.

> -Andi

cu
Adrian

-- 

       "Is there not promise of rain?" Ling Tan asked suddenly out
        of the darkness. There had been need of rain for many days.
       "Only a promise," Lao Er said.
                                       Pearl S. Buck - Dragon Seed


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Re: [KJ] janitor project: fix gcc 4 warnings

[Andi Kleen]

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On Mon, Dec 20, 2004 at 12:15:39AM +0200, Alexey Dobriyan wrote:
> On Sunday 19 December 2004 21:09, Andi Kleen wrote:
> 
> > make allmodconfig
> > make CC=/usr/local/gcc4/bin/gcc 2>&1 | tee LOG
> 
>   CC      kernel/acct.o
> kernel/acct.c: In function ???encode_float???:
> kernel/acct.c:366: fatal error: internal consistency failure
> compilation terminated.

Looks like another gcc bug. I will file a gcc bug thanks. 

Just disable accounting in the .config to continue or use make -k 


> 
> here.
> 
> Maaaany "differ in signedness" warnings.

Yep, and some new "bla is uninitialized" warnings. Many of them 
are bogus, because gcc just cannot prove if a variable is 
uninitialized or not and it now does it for structure fields
too. Anyways, they all need to be examined and fixed.

> ===============================================================================
> init/main.c: In function ???maxcpus???:
> init/main.c:150: warning: pointer targets in passing argument 2 of ???get_option??? 
> differ in signedness
> ===============================================================================
> unsigned int maxcpus;
> int get_option(char **str, int *pint);
> ...
> get_option(&str, &max_cpus);
> ===============================================================================
> For example, this one should be left as is, shouldn't it?


The warning should be fixed, otherwise the warning noise will
hide real valuable warnings. It's a judgement call whether you
modify the function prototype or the argument. In this case
both would be possible. I would usually do the change that
requires less work (e.g. fix the argument in this case because
there are a lot more get_option callers). This means make maxcpus
an int. Please avoid adding casts if possible. 

-Andi


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Re: [KJ] janitor project: fix gcc 4 warnings

[Andi Kleen]

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On Mon, Dec 20, 2004 at 01:13:16AM +0100, Adrian Bunk wrote:
> > You'll see lots of warnings in LOG. Fix them all and submit patches
> > through the usual janitor channels.
> 
> What kind of new warnings does gcc 4.0 emit?

http://www.firstfloor.org/~andi/2.6.10rc2-gcc4-warnings.gz has a full
list from i386 allmodconfig (including some errors) 

> Altogether, new warnings in gcc 4.0 might be a nice diagnostics for the 
> people who are also trying to find bugs using -W, but I don't see urgent 
> reasons for fixing them before gcc 4.0 is actually released.

I disagree. It's better to have the kernel already gcc 4 ready when it is 
released. And we always ask other people to test mainline kernels, so 
it's only fair to test and use other people's mainline code too.

-Andi

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Re: [KJ] janitor project: fix gcc 4 warnings

[Andi Kleen]

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On Mon, Dec 20, 2004 at 12:15:39AM +0200, Alexey Dobriyan wrote:
> On Sunday 19 December 2004 21:09, Andi Kleen wrote:
> 
> > make allmodconfig
> > make CC=/usr/local/gcc4/bin/gcc 2>&1 | tee LOG
> 
>   CC      kernel/acct.o
> kernel/acct.c: In function ???encode_float???:
> kernel/acct.c:366: fatal error: internal consistency failure
> compilation terminated.

I checked this and it doesn't seem to happen with my compiler
(which is a newer CVS checkout). So I assume it has been fixed already.

-Andi

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Re: [KJ] janitor project: fix gcc 4 warnings

[Arnd Bergmann]

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On Sünndag 19 Dezember 2004 20:47, Matthew Wilcox wrote:
> On Sun, Dec 19, 2004 at 08:09:03PM +0100, Andi Kleen wrote:
> > Here's a proposed janitor project if anybody is interested:
> > 
> > The current gcc 4.0 snapshots include some more warnings in -Wall
> > and changed some existing ones which makes a kernel compilation quite noisy. 
> 
> I think it would get more takers if people didn't have to compile a new
> gcc.  If we had a list of -W... flags in older gccs that could simulate
> 90% of the warnings, this would make it possible for more people to work
> on it.

Maybe someone can make gcc-4 build logs available similar to the ones at
http://developer.osdl.org/cherry/compile/. In many cases it's not even
necessary to produce the warning with your own compiler in order to fix
it. This could also be combined with warnings from the various sparse-like
code checkers.

 Arnd <><



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Re: [KJ] janitor project: fix gcc 4 warnings

[Kovarththanan Rajaratnam]

Hey

"Andi Kleen" <ak@muc.de> wrote in message
news:20041220080406.GB47521@muc.de...
> >   CC      kernel/acct.o
> > kernel/acct.c: In function ???encode_float???:
> > kernel/acct.c:366: fatal error: internal consistency failure
> > compilation terminated.
>
> I checked this and it doesn't seem to happen with my compiler
> (which is a newer CVS checkout). So I assume it has been fixed already.
>
I just tried to make a new CVS checkout, but I still get the 'internal
consistency failure'. Any advice on what to do?

--
Best Regards
Kovarththanan Rajaratnam





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Re: [KJ] janitor project: fix gcc 4 warnings

[Randy.Dunlap]

S wrote:
> Using gcc-core-4.0-20050130.tar, the "internal
> consisteny problem" has gone away.
> However, during the 2.6.10 kernel compilation, some
> #warnings stopped the compilation. Any ideas on what
> needs to be done with the #warnings ?
>>From the looks of it, a newer snapshot may not have
> the  #warnings possibly.

What CPU arch. are you building on?
I see that sparc64 and alpha use -Werror (treat warnings
as errors, which is what you show below), but other arches
don't do that (unless it's in -mm) AFAIK.

If you are using sparc64 or alpha, you can just edit
the Makefile(s) to use -Wall instead of -Werror .
Or change .config to omit these (few) drivers.

> <snip>
> drivers/cpufreq/cpufreq_userspace.c:140:2: warning:
> #warning The /proc/sys/cpu/ and sysctl interface to
> cpufreq will be removed from the 2.6. kernel series
> soon after 2005-01-01
>   CC [M]  drivers/cpufreq/cpufreq_ondemand.o
>   CC [M]  drivers/cpufreq/freq_table.o
>   CC [M]  drivers/cpufreq/proc_intf.o
> drivers/cpufreq/proc_intf.c:15:2: warning: #warning
> This module will be removed
> from the 2.6. kernel series soon after 2005-01-01
>   GEN     drivers/eisa/devlist.h
>   CC      drivers/eisa/eisa-bus.o
> cc1: warnings being treated as errors
> drivers/eisa/eisa-bus.c:421: warning: pointer targets
> in initialization differ in signedness
> drivers/eisa/eisa-bus.c:422: warning: pointer targets
> in initialization differ in signedness
> make[2]: *** [drivers/eisa/eisa-bus.o] Error 1
> make[1]: *** [drivers/eisa] Error 2
> make: *** [drivers] Error 2
> 
> 
> -----------------------------------------------------
> List:       kernel-janitor-discuss
> Subject:    [KJ] janitor project: fix gcc 4 warnings
> From:       Andi Kleen <ak () muc ! de>
> Date:       2004-12-19 19:09:03
> Message-ID: <20041219190903.GA30192 () muc ! de>
> [Download message RAW]
> 
> Here's a proposed janitor project if anybody is
> interested:
> 
> The current gcc 4.0 snapshots include some more
> warnings in -Wall
> and changed some existing ones which makes a kernel
> compilation quite noisy. 
> 
> The project would be to fix all these warnings.
> 
> Short howto: 
> 
> Get
> ftp://gcc.gnu.org/pub/gcc/snapshots/4.0-20041219/gcc-core-4.0-20041219.tar.bz2
> 
> Untar it and compile with 
> 
> mkdir obj
> ../gcc-*/configure --disable-checking
> --enable-languages=c --prefix=/usr/local/gcc4
> make bootstrap
> <as root> 
> make install
> 
> 
> Then compile an uptodate 2.6 kernel with:
> 
> make allmodconfig
> make CC=/usr/local/gcc4/bin/gcc 2>&1 | tee LOG
> grep warning LOG 
> 
> You'll see lots of warnings in LOG. Fix them all and
> submit patches
> through the usual janitor channels.
> 
> -Andi


-- 
~Randy
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Re: [KJ] janitor project: fix gcc 4 warnings

[devzero]

Hello !

i recognized that there are still quite a reasonable number of warnings when i compile a kernel, especially with allmodconfig.

is there somebody systematically working on fixing those warnings being left over in kernel source ?

i´m really a newbie to kernel development and not really a good C programmer, but i`d like to try to help fix those warnings. maybe this will freshen up my programming skills a little bit.

btw - http://developer.osdl.org/cherry/compile/ seems to be very outdated - wouldn´t it be good to monitor the "warnings regression" between kernel releases?

whenever i compile a kernel, i move that window to my second screen and whenever gcc spits out a warning, this draws someone`s attention. leaving that feeling "uuuhhh, ohhh - there must be something wrong with the kernel...."

so, is this the right place to discuss such fixes ?
anybody to volunteer on systematically fixing those warnings ?

regards
roland

sysadmin


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