colinux-users

[coLinux-users] Re: floating point problems (was: using 2.6 kernels, moving to latest coLinux snapshot, etc.)

[gboutwel <gbo...@pr...>]

sl...@bl... wrote:

> Joe Wells  writes:



> What is puzzling me is that I don't understand why only Firefox

> is affected by this.  I am running many other programs that
use floating

> point and none of them have this problem.  Gnumeric uses many
of

> the  same libraries as Firefox (I am building Firefox against
GTK2)

> and it seems to run.  (Actually, it crashes the first time
I run it (no

> idea why because the Gnome software helpfully hides the cause
and pops

> up a window saying it has crashed but without giving the signal),
but

> then if I run it immediately afterward it runs fine.  This
is new since

> the upgrade to the coLinux 2004-07-19 snapshot.  Strange.)
 GV also

> runs fine, and it surely is doing a lot of floating point operations

> to scale and render fonts.

> 

> Comments?



Joe,



  Did you emerge or re-emerge firefox after updating to the new
snapshot?  We have another person on IRC who reported getting
FPEs all of a sudden.  He changed his cflags to something a little
safer and re-emerged his system with the new cflags and he no
longer gets FPEs.  I've been using the latest sources including
the changes in the 07/19 snapshot for like a month now, on Gentoo
with out a single FPE.  I just emerged firefox and I don't see
any FPE while I'm using it at all.



  Is it possible that the prior versions of coLinux allowed FP
operations that shouldn't have been allowed and now that we've
fixed that, it's identifying a situation that was being allowed
but shouldn't have been in FireFox?  The only significant change
between 0.6.1 and 0719 in regards to FP operations was that flop20
didn't pass and now does.



George



--------------------------------

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Search for it in Praize Bible

http://www.praize.com/bible/

Re: [coLinux-users] Re: floating point problems (was: using 2.6 kernels, moving to latest coLinux snapshot, etc.)

[Peng <rin...@gm...>]

Could you please let me know what is the safe CFLAGS for gentoo you mentioned?

Thanks,

-- Peng

On 18 Aug 2004 13:24:21 -0000, gboutwel <gbo...@pr...> wrote:
>   Did you emerge or re-emerge firefox after updating to the new
> snapshot?  We have another person on IRC who reported getting
> FPEs all of a sudden.  He changed his cflags to something a little
> safer and re-emerged his system with the new cflags and he no
> longer gets FPEs.  I've been using the latest sources including
> the changes in the 07/19 snapshot for like a month now, on Gentoo
> with out a single FPE.  I just emerged firefox and I don't see
> any FPE while I'm using it at all.
>

Re: [coLinux-users] Re: floating point problems (was: using 2.6 kernels, moving to latest coLinux snapshot, etc.)

[<sl...@bl...>]

"gboutwel" <gbo...@pr...> writes:

> sl...@bl... wrote:
> 
> > What is puzzling me is that I don't understand why only Firefox is
> > affected by this.  I am running many other programs that use
> > floating point and none of them have this problem.  Gnumeric uses
> > many of the same libraries as Firefox (I am building Firefox
> > against GTK2) and it seems to run.  (Actually, it crashes the
> > first time I run it (no idea why because the Gnome software
> > helpfully hides the cause and pops up a window saying it has
> > crashed but without giving the signal), but then if I run it
> > immediately afterward it runs fine.  This is new since the upgrade
> > to the coLinux 2004-07-19 snapshot.  Strange.)  GV also runs fine,
> > and it surely is doing a lot of floating point operations to scale
> > and render fonts.
> >
> > Comments?
>
>   Did you emerge or re-emerge firefox after updating to the new
> snapshot?

No and yes.  "No" in the sense that the old build of Firefox (from
before switching from coLinux 0.6.1 to the new snapshot) exhibits the
problem.  "Yes" in the sense that I then tried building a new version
of Firefox to see if the problem might go away.  Both the old version
and the new version fail in the same way.  I still have them both on
my system.

By the way, I have discovered that Xdvi also has the problem.  It was
built before I switched to the coLinux snapshot.

> We have another person on IRC who reported getting
> FPEs all of a sudden.  He changed his cflags to something a little
> safer and re-emerged his system with the new cflags and he no
> longer gets FPEs.

I recompiled the .o files where Firefox was crashing with "-O0" (no
optimization at all, only using i386 features and not extra features
of Pentium 4) and it didn't help.  The only thing that helped was
recompiling those .o files with "-msoft-float -mno-fp-ret-in-387
-lfp-bit" (where libfp-bit.a is a library for doing floating point
operations in software).  However, even recompiling all of the .o
files of Firefox didn't seem to be enough because it still crashed in
.o files from shared libraries.

Did the person you mention re-emerge his *entire* system?  Firefox
uses these shared libraries:

  linux-gate.so.1 libmozjs.so libxpcom.so libplds4.so libplc4.so
  libnspr4.so libpthread.so.0 libdl.so.2 libgtk-x11-2.0.so.0
  libgdk-x11-2.0.so.0 libatk-1.0.so.0 libgdk_pixbuf-2.0.so.0
  libpangoxft-1.0.so.0 libpangox-1.0.so.0 libpango-1.0.so.0
  libgobject-2.0.so.0 libgmodule-2.0.so.0 libglib-2.0.so.0 libX11.so.6
  libm.so.6 libstdc++.so.5 libgcc_s.so.1 libc.so.6 /lib/ld-linux.so.2
  libXrandr.so.2 libXi.so.6 libXinerama.so.1 libXext.so.6 libXft.so.2
  libfreetype.so.6 libXrender.so.1 libfontconfig.so.1 libXcursor.so.1
  libpangoft2-1.0.so.0 libexpat.so.0 libz.so.1

I'd rather not have to recompile all of these libraries, especially
since they worked fine with coLinux 0.6.1 and Linux kernel 2.4.

> I've been using the latest sources including
> the changes in the 07/19 snapshot for like a month now, on Gentoo
> with out a single FPE.  I just emerged firefox and I don't see
> any FPE while I'm using it at all.

What is your CPU?  On my system, /proc/cpuinfo reveals:

  processor       : 0
  vendor_id       : GenuineIntel
  cpu family      : 6
  model           : 9
  model name      : Intel(R) Pentium(R) M processor 1100MHz
  stepping        : 5
  cpu MHz         : 0.000
  cache size      : 1024 KB
  fdiv_bug        : no
  hlt_bug         : no
  f00f_bug        : no
  coma_bug        : no
  fpu             : yes
  fpu_exception   : yes
  cpuid level     : 2
  wp              : yes
  flags           : fpu vme de pse tsc msr mce cx8 sep mtrr pge mca cmov pat clflush dts acpi mmx fxsr sse sse2 tm pbe tm2 est
  bogomips        : 766.77

I find it interesting that the other person who recently sent e-mail
about problems also has a "Intel Pentium M processor 1100MHz".

> Is it possible that the prior versions of coLinux allowed FP
> operations that shouldn't have been allowed and now that we've
> fixed that, it's identifying a situation that was being allowed
> but shouldn't have been in FireFox?

This seems doubtful.  Under the debugger, it is clear that things are
going horribly wrong with straightforward instructions to merely load
floating point values into floating point registers from memory or
convert values in floating point registers into integers and store
them into memory.  I don't think movsd or cvttsd2si are extra or
unusual operations.

> The only significant change
> between 0.6.1 and 0719 in regards to FP operations was that flop20
> didn't pass and now does.

Where do I get flops20 so I can try it on my machine?  Is it available
as a Gentoo ebuild?  "emerge search flops" and "emerge search float"
do not reveal it.

Thanks a lot for your advice!

-- 
Joe

Re: [coLinux-users] Re: floating point problems (was: using 2.6 kernels, moving to latest coLinux snapshot, etc.)

[Peng <rin...@gm...>]

I also had the xdvi crash problem with my Pentium M machine using the
0710 snapshot.  I re-emerged tetex and the problem was still there. 
Then, I re-emerged xfree and the problem is gone!! Here's what I did:

(don't put "mmx" or "sse" in the USE flags)
USE="X -kde -gnome -qt"
CFLAGS="-Os -march=i686 -pipe"

These flags are certainly conservative, but they seem to work.  At
least xdvi doesn't crash anymore.

-- Peng

On 19 Aug 2004 14:42:26 +0100, Joe Wells (reverse mailbox letters to
reply) <sl...@bl...> wrote:
> "gboutwel" <gbo...@pr...> writes:
> 
> > sl...@bl... wrote:
> >
> > > What is puzzling me is that I don't understand why only Firefox is
> > > affected by this.  I am running many other programs that use
> > > floating point and none of them have this problem.  Gnumeric uses
> > > many of the same libraries as Firefox (I am building Firefox
> > > against GTK2) and it seems to run.  (Actually, it crashes the
> > > first time I run it (no idea why because the Gnome software
> > > helpfully hides the cause and pops up a window saying it has
> > > crashed but without giving the signal), but then if I run it
> > > immediately afterward it runs fine.  This is new since the upgrade
> > > to the coLinux 2004-07-19 snapshot.  Strange.)  GV also runs fine,
> > > and it surely is doing a lot of floating point operations to scale
> > > and render fonts.
> > >
> > > Comments?
> >
> >   Did you emerge or re-emerge firefox after updating to the new
> > snapshot?
> 
> No and yes.  "No" in the sense that the old build of Firefox (from
> before switching from coLinux 0.6.1 to the new snapshot) exhibits the
> problem.  "Yes" in the sense that I then tried building a new version
> of Firefox to see if the problem might go away.  Both the old version
> and the new version fail in the same way.  I still have them both on
> my system.
> 
> By the way, I have discovered that Xdvi also has the problem.  It was
> built before I switched to the coLinux snapshot.
> 
> > We have another person on IRC who reported getting
> > FPEs all of a sudden.  He changed his cflags to something a little
> > safer and re-emerged his system with the new cflags and he no
> > longer gets FPEs.
> 
> I recompiled the .o files where Firefox was crashing with "-O0" (no
> optimization at all, only using i386 features and not extra features
> of Pentium 4) and it didn't help.  The only thing that helped was
> recompiling those .o files with "-msoft-float -mno-fp-ret-in-387
> -lfp-bit" (where libfp-bit.a is a library for doing floating point
> operations in software).  However, even recompiling all of the .o
> files of Firefox didn't seem to be enough because it still crashed in
> ..o files from shared libraries.
> 
> Did the person you mention re-emerge his *entire* system?  Firefox
> uses these shared libraries:
> 
>   linux-gate.so.1 libmozjs.so libxpcom.so libplds4.so libplc4.so
>   libnspr4.so libpthread.so.0 libdl.so.2 libgtk-x11-2.0.so.0
>   libgdk-x11-2.0.so.0 libatk-1.0.so.0 libgdk_pixbuf-2.0.so.0
>   libpangoxft-1.0.so.0 libpangox-1.0.so.0 libpango-1.0.so.0
>   libgobject-2.0.so.0 libgmodule-2.0.so.0 libglib-2.0.so.0 libX11.so.6
>   libm.so.6 libstdc++.so.5 libgcc_s.so.1 libc.so.6 /lib/ld-linux.so.2
>   libXrandr.so.2 libXi.so.6 libXinerama.so.1 libXext.so.6 libXft.so.2
>   libfreetype.so.6 libXrender.so.1 libfontconfig.so.1 libXcursor.so.1
>   libpangoft2-1.0.so.0 libexpat.so.0 libz.so.1
> 
> I'd rather not have to recompile all of these libraries, especially
> since they worked fine with coLinux 0.6.1 and Linux kernel 2.4.
> 
> > I've been using the latest sources including
> > the changes in the 07/19 snapshot for like a month now, on Gentoo
> > with out a single FPE.  I just emerged firefox and I don't see
> > any FPE while I'm using it at all.
> 
> What is your CPU?  On my system, /proc/cpuinfo reveals:
> 
>   processor       : 0
>   vendor_id       : GenuineIntel
>   cpu family      : 6
>   model           : 9
>   model name      : Intel(R) Pentium(R) M processor 1100MHz
>   stepping        : 5
>   cpu MHz         : 0.000
>   cache size      : 1024 KB
>   fdiv_bug        : no
>   hlt_bug         : no
>   f00f_bug        : no
>   coma_bug        : no
>   fpu             : yes
>   fpu_exception   : yes
>   cpuid level     : 2
>   wp              : yes
>   flags           : fpu vme de pse tsc msr mce cx8 sep mtrr pge mca cmov pat clflush dts acpi mmx fxsr sse sse2 tm pbe tm2 est
>   bogomips        : 766.77
> 
> I find it interesting that the other person who recently sent e-mail
> about problems also has a "Intel Pentium M processor 1100MHz".
> 
> > Is it possible that the prior versions of coLinux allowed FP
> > operations that shouldn't have been allowed and now that we've
> > fixed that, it's identifying a situation that was being allowed
> > but shouldn't have been in FireFox?
> 
> This seems doubtful.  Under the debugger, it is clear that things are
> going horribly wrong with straightforward instructions to merely load
> floating point values into floating point registers from memory or
> convert values in floating point registers into integers and store
> them into memory.  I don't think movsd or cvttsd2si are extra or
> unusual operations.
> 
> > The only significant change
> > between 0.6.1 and 0719 in regards to FP operations was that flop20
> > didn't pass and now does.
> 
> Where do I get flops20 so I can try it on my machine?  Is it available
> as a Gentoo ebuild?  "emerge search flops" and "emerge search float"
> do not reveal it.
> 
> Thanks a lot for your advice!
> 
> --
> Joe
> 
> 
> 
> 
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Re: [coLinux-users] Re: floating point problems (was: using 2.6 kernels, moving to latest coLinux snapshot, etc.)

[<sl...@bl...>]

sl...@bl... (Joe Wells (reverse mailbox letters to reply)) writes:

> "gboutwel" <gbo...@pr...> writes:
> 
> > The only significant change
> > between 0.6.1 and 0719 in regards to FP operations was that flop20
> > didn't pass and now does.
> 
> Where do I get flops20 so I can try it on my machine?  Is it available
> as a Gentoo ebuild?  "emerge search flops" and "emerge search float"
> do not reveal it.

Does anyone know where I get this floating point test suite?  It has
been referred to as "fops20" and "flop20" in e-mail on this mailing
list.

-- 
Thanks,

Joe

Re: [coLinux-users] Re: floating point problems (was: using 2.6 kernels, moving to latest coLinux snapshot, etc.)

[Nuno L. <lu...@nl...>]

Joe Wells, dando pulos de alegria, escreveu :
> sl...@bl... (Joe Wells (reverse mailbox letters to reply)) writes:
>>"gboutwel" <gbo...@pr...> writes:
>>>The only significant change
>>>between 0.6.1 and 0719 in regards to FP operations was that flop20
>>>didn't pass and now does.
>>
>>Where do I get flops20 so I can try it on my machine?  Is it available
>>as a Gentoo ebuild?  "emerge search flops" and "emerge search float"
>>do not reveal it.
> 
> Does anyone know where I get this floating point test suite?  It has
> been referred to as "fops20" and "flop20" in e-mail on this mailing
> list.

Dan Aloni gave me a link to it but I don't remember anymore. You should 
find it easily with google, but you can also get it at 
http://nlucas.homeip.net/colinux/test/flops20.zip (it is my home pc, so 
it is possible the net be down or something).

After some googling I found this last year forums about the pentium 4 
CFLAGS problems with floating point:

http://www.gentoo.org/news/en/gwn/20030401-newsletter.xml#doc_chap4

It seems one way of testing if you have a gentoo configuration that 
activates this gcc bugs is executing:

  # python -c 'int(10.1); int(10000.3); int(1.2)'

If it doesn't show nothing (no error) it is because your configuration 
is ok (or you have a mixed compiled environment, off course).

Regards,
~Nuno Lucas

Re: [coLinux-users] Re: floating point problems (was: using 2.6 kernels, moving to latest coLinux snapshot, etc.)

[<sl...@bl...>]

Nuno Lucas <lu...@nl...> writes:

> Joe Wells, dando pulos de alegria, escreveu :
> > sl...@bl... (Joe Wells (reverse mailbox letters to reply)) writes:
> >>"gboutwel" <gbo...@pr...> writes:
> >>>The only significant change
> >>>between 0.6.1 and 0719 in regards to FP operations was that flop20
> >>>didn't pass and now does.
> >>
> >>Where do I get flops20 so I can try it on my machine?  Is it available
> >>as a Gentoo ebuild?  "emerge search flops" and "emerge search float"
> >>do not reveal it.
> > Does anyone know where I get this floating point test suite?  It has
> > been referred to as "fops20" and "flop20" in e-mail on this mailing
> > list.
> 
> Dan Aloni gave me a link to it but I don't remember anymore. You
> should find it easily with google, but you can also get it at
> http://nlucas.homeip.net/colinux/test/flops20.zip (it is my home pc,
> so it is possible the net be down or something).

Thanks very much for the pointer to flops20!

> After some googling I found this last year forums about the pentium 4
> CFLAGS problems with floating point:
> 
> http://www.gentoo.org/news/en/gwn/20030401-newsletter.xml#doc_chap4
> 
> It seems one way of testing if you have a gentoo configuration that
> activates this gcc bugs is executing:
> 
>   # python -c 'int(10.1); int(10000.3); int(1.2)'

This runs fine for me.

> If it doesn't show nothing (no error) it is because your configuration
> is ok (or you have a mixed compiled environment, off course).

After looking at this earlier discussion, it is clear to me that it is
unrelated to the problem I am reporting.  The key differences are:

1. The earlier discussion is from 2003-04 and earlier (more than 16
   months ago) and refers to GCC version 3.2.  In many places, it
   states that the bugs are going to be fixed in GCC 3.3, and I am now
   using GCC 3.3.4.

2. The earlier discussion does not observe any connection with linking
   with libpthreads.  The problem I am reporting only happens to
   programs that are linked with libpthreads.

3. The earlier discussion does not refer to any difference between
   Linux kernel versions.  It also (obviously) does not mention
   coLinux.  The problem I am reporting only happens with pre-0.6.2
   coLinux snapshots using Linux kernel 2.6.7 and does not happen with
   coLinux 0.6.1 using Linux kernel 2.4.26.

Thanks for pointing out the earlier discussion though.

-- 
Joe