Re: [ECOS] Re: eCos arm-eabi GNU tools - test release 4.6.2-20120125

[Sergei Gavrikov <sg@scanex.ru>]

On Fri, 24 Feb 2012, Grant Edwards wrote:

> FWIW, I just tried the new tools building a fairly simple eCos kernel
> (based on CVS HEAD from a couple weeks ago) with FreeBSD stack
> enabled.  The kernel build generated 172 compiler warnings.  About
> half of those (89) are aliasing violations in the bsd stack source
> code, so it looks like '-fno-strict-aliasing' needs to be added to the
> compiler flags for the FreeBSD stack to safely use the new toolchain.
> 
> Of the remaining warnings, about half (45) are variables that are set
> but never used.  Most of them are in the FreeBSD stack, but there are
> a smattering of them in other places as well.
> 
> The remaining warnings a variety things like printf format/arg
> mismatches, failed inlines, signed/unsigned mismatches, and so on.
> 
> Personally, I'm not comfortable shipping anything that builds with
> that many warnings.  For my code, the requirement is zero warnings.
> For eCos code, the number of warnings has to be small enough that I
> can anlyze them once and thereafter tell at a glance whether any new
> ones have popped up.
 
Hm. My score is something 1/4 from yours. For the same eCos template
and *arm-eabi* eCos target (one from officially supported *arm-eabi*
targets from eCos AnonCVS):

  % make 2>&1 | tee log && make IGNORE_LINK_ERRORS=y tests 2>&1 | tee -a log
  % grep warning: log | wc -l
  49
  % grep warning: log | grep -v -- unused-but-set | wc -l
  3

So, the most (46) are:

  warning: variable "foo" set but not used [-Wunused-but-set-variable]

And that is new warning from -Wall set
http://gcc.gnu.org/gcc-4.6/porting_to.html

IMHO, those warnings is not big issue. I hope that we will be able to
rid all of them. Also there were a few *notes* that mangling of va_list
has changed in GCC 4.4.

Grant, did you try *arm-eabi* toolchain for your target before?  Of
course, if this is possible. I mean stable arm-eabi (4.3.2) toolchain
from eCosCentric? May be you missed that CFLAGS clean-up step on 4.3.2
migration?

BTW, I have the very few warnings when I use stable arm-eabi (4.3.2)
toolchain from eCosCentric with CFLAGS updated since eCos 3.0.

> Doing the same build with my old 3.2.x toolchain generates 6 warnings
> that I've never gotten around to fixing -- but I'm familiar with them
> and know they're harmless.
 
Ah! So, you used old 'arm-elf' toolchain before.  As far I remember
CFLAGS for all *arm-eabi* targets in eCos AnonCVS were fixed in those
days (pre eCos 3.0 days). Well, there are a few *arm-elf* targets in
eCos AnonCVS.  As I could see *arm-elf* based are sa11x0, pid, aeb, and
ebsa285.

Well, I believe that we will rid all warnings at the end :-) More
warnings means that the newest compiler is more pedantic and IMHO, that
is good for programmers, but not for their elder code :-)

Sergei

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