[RFC PATCH] x86: don't compile with gcc-3.3.3

[RFC PATCH] x86: don't compile with gcc-3.3.3

[florian]

hpa commented on bug 16506[1] :
"Please note that gcc-3.3.3 is known broken on x86; gcc-3.4 is the oldest
version which is known to *not* be broken."

References: 
	[0]: https://bugzilla.kernel.org/show_bug.cgi?id=16633
	[1]: https://bugzilla.kernel.org/show_bug.cgi?id=16506#c28

If that is indeed so, we should abort the build? No?


---
 arch/x86/Makefile |    8 +++++++-
 1 files changed, 7 insertions(+), 1 deletions(-)

diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 8aa1b59..1eb2d99 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -153,7 +153,7 @@ all: bzImage
 # KBUILD_IMAGE specify target image being built
 KBUILD_IMAGE := $(boot)/bzImage
 
-bzImage: vmlinux
+bzImage: checkgccversion vmlinux
 ifeq ($(CONFIG_X86_DECODER_SELFTEST),y)
 	$(Q)$(MAKE) $(build)=arch/x86/tools posttest
 endif
@@ -172,6 +172,12 @@ PHONY += vdso_install
 vdso_install:
 	$(Q)$(MAKE) $(build)=arch/x86/vdso $@
 
+checkgccversion:
+	$(Q)if test "$(call cc-fullversion)" = "040403" ; then \
+		echo "*** GCC-3.3.3 is known broken. Please upgrade." ; \
+		echo "*** GCC-3.4 is the earliest version known *not* broken." ; \
+		false ; \
+	fi
 archclean:
 	$(Q)rm -rf $(objtree)/arch/i386
 	$(Q)rm -rf $(objtree)/arch/x86_64
-- 
1.7.2

Re: [RFC PATCH] x86: don't compile with gcc-3.3.3

[Peter Zijlstra]

On Mon, 2010-09-13 at 10:31 +0200, florian@mickler.org wrote:
> hpa commented on bug 16506[1] :
> "Please note that gcc-3.3.3 is known broken on x86; gcc-3.4 is the oldest
> version which is known to *not* be broken."
> 
> References: 
> 	[0]: https://bugzilla.kernel.org/show_bug.cgi?id=16633
> 	[1]: https://bugzilla.kernel.org/show_bug.cgi?id=16506#c28
> 
> If that is indeed so, we should abort the build? No?

Does it in fact still build with 3.4? I seem to recall some talk about
pushing the minimum version to 4.x for x86, although I can't remember
where..

Re: [RFC PATCH] x86: don't compile with gcc-3.3.3

[H. Peter Anvin]

On 09/13/2010 01:39 AM, Peter Zijlstra wrote:
> On Mon, 2010-09-13 at 10:31 +0200, florian@mickler.org wrote:
>> hpa commented on bug 16506[1] :
>> "Please note that gcc-3.3.3 is known broken on x86; gcc-3.4 is the oldest
>> version which is known to *not* be broken."
>>
>> References: 
>> 	[0]: https://bugzilla.kernel.org/show_bug.cgi?id=16633
>> 	[1]: https://bugzilla.kernel.org/show_bug.cgi?id=16506#c28
>>
>> If that is indeed so, we should abort the build? No?
> 
> Does it in fact still build with 3.4? I seem to recall some talk about
> pushing the minimum version to 4.x for x86, although I can't remember
> where..

It does indeed still build with 3.4, although it is giving us a bunch of
headaches to *make it so*, and I would personally be really glad if the
consensus is we can just axe it.

The only reason to not abort the build for gcc 3.3.3 is that soem
"enterprise" distros have been shipping gcc 3.3.3 with backported fixes
from 3.4, which of course still identifies themselves as gcc 3.3.3, and
so technically it is iompossioble to tell if any particular "gcc 3.3.3"
is actually broken or not.

However, as far as I can tell, most of the people who build current x86
kernels with gcc 3.x are people who are testing building current kernels
with gcc 3.x.  Some of the embedded systems are different, because for
some strange reasons most of the embedded world seem stuck on gcc 3.4 or so.

	-hpa

-- 
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel.  I don't speak on their behalf.

Re: [RFC PATCH] x86: don't compile with gcc-3.3.3

[Florian Mickler]

On Mon, 13 Sep 2010 08:56:39 -0700
"H. Peter Anvin" <hpa@zytor.com> wrote:

> On 09/13/2010 01:39 AM, Peter Zijlstra wrote:
> > On Mon, 2010-09-13 at 10:31 +0200, florian@mickler.org wrote:
> >> hpa commented on bug 16506[1] :
> >> "Please note that gcc-3.3.3 is known broken on x86; gcc-3.4 is the oldest
> >> version which is known to *not* be broken."
> >>
> >> References: 
> >> 	[0]: https://bugzilla.kernel.org/show_bug.cgi?id=16633
> >> 	[1]: https://bugzilla.kernel.org/show_bug.cgi?id=16506#c28
> >>
> >> If that is indeed so, we should abort the build? No?
> > 
> > Does it in fact still build with 3.4? I seem to recall some talk about
> > pushing the minimum version to 4.x for x86, although I can't remember
> > where..
> 
> It does indeed still build with 3.4, although it is giving us a bunch of
> headaches to *make it so*, and I would personally be really glad if the
> consensus is we can just axe it.
> 
> The only reason to not abort the build for gcc 3.3.3 is that soem
> "enterprise" distros have been shipping gcc 3.3.3 with backported fixes
> from 3.4, which of course still identifies themselves as gcc 3.3.3, and
> so technically it is iompossioble to tell if any particular "gcc 3.3.3"
> is actually broken or not.
> 
> However, as far as I can tell, most of the people who build current x86
> kernels with gcc 3.x are people who are testing building current kernels
> with gcc 3.x.  Some of the embedded systems are different, because for
> some strange reasons most of the embedded world seem stuck on gcc 3.4 or so.

Well, all _I_ can add, that there are people (2 I know
from the above bug reports to be precise) who spent hours (? well I
guess, at least some minutes) debugging old gcc bugs and just to have
some (please take no offense, I'm just trying to tell how it must look
to them) random guy tell them in the bugzilla "na na, we know about this
already and we don't fix it, na na" ...

Also the patch above checks actually for 4.4.3 which is obvioulsy
wrong ;) 

The enterprise distro issue is a little bit of an annoyance.. but they
should perhaps give us an opportunity to distinguish between their
(working) gcc and the stock broken one. I'm totally not opposed to any
ugly hack to make that distinguishing over here. But not fixing the
issues above seems to hurt the mainline linux kernel.

Cheers,
Flo

> 
> 	-hpa
> 

Re: [RFC PATCH] x86: don't compile with gcc-3.3.3

[Florian Mickler]

On Mon, 13 Sep 2010 18:21:05 +0200
Florian Mickler <florian@mickler.org> wrote:

> On Mon, 13 Sep 2010 08:56:39 -0700
> "H. Peter Anvin" <hpa@zytor.com> wrote:
> 
> > On 09/13/2010 01:39 AM, Peter Zijlstra wrote:

> > The only reason to not abort the build for gcc 3.3.3 is that soem
> > "enterprise" distros have been shipping gcc 3.3.3 with backported fixes
> > from 3.4, which of course still identifies themselves as gcc 3.3.3, and
> > so technically it is iompossioble to tell if any particular "gcc 3.3.3"
> > is actually broken or not.

What about issuing a warning like 

"gcc 3.3.3 is broken because of bug [bugdescription/url].
if you know your build is not affected by this bug do:
touch .gcc333bugfixNNNN but please be aware that you are 
not supported by the mainline kernel development comunity 
if you do"

and implementing the accompanying logic?

Cheers,
Flo

Re: [RFC PATCH] x86: don't compile with gcc-3.3.3

[Russell King - ARM Linux]

On Mon, Sep 13, 2010 at 10:39:55AM +0200, Peter Zijlstra wrote:
> On Mon, 2010-09-13 at 10:31 +0200, florian@mickler.org wrote:
> > hpa commented on bug 16506[1] :
> > "Please note that gcc-3.3.3 is known broken on x86; gcc-3.4 is the oldest
> > version which is known to *not* be broken."
> > 
> > References: 
> > 	[0]: https://bugzilla.kernel.org/show_bug.cgi?id=16633
> > 	[1]: https://bugzilla.kernel.org/show_bug.cgi?id=16506#c28
> > 
> > If that is indeed so, we should abort the build? No?
> 
> Does it in fact still build with 3.4? I seem to recall some talk about
> pushing the minimum version to 4.x for x86, although I can't remember
> where..

I'm still building kernels with gcc 3.4.3 (for the ARMs which don't
require a later compiler) or gcc 4.3.2+patches for those which do.

ARM gcc 3.4.3 is certainly noticably faster than gcc 4.3.2 even on
x86 - and as long as ARM gcc 3.4.3 works, and there's not great pain
in allowing it to build the arch-independent stuff, I see no reason
to deny it across the entire kernel build.

I think we should have a minimum compiler version for the generic
kernel, and individual minimum compiler versions for the architectures,
so that arches can specify a higher minimum compiler version if they
have specific problems there.

Re: [RFC PATCH] x86: don't compile with gcc-3.3.3

[H. Peter Anvin]

On 09/13/2010 09:28 AM, Florian Mickler wrote:
> 
> What about issuing a warning like 
> 
> "gcc 3.3.3 is broken because of bug [bugdescription/url].
> if you know your build is not affected by this bug do:
> touch .gcc333bugfixNNNN but please be aware that you are 
> not supported by the mainline kernel development comunity 
> if you do"
> 
> and implementing the accompanying logic?
> 

URK.

The workload of maintaining that crap would be astonishing, especially
for something at the tail end of supportable.

I don't think that is even remotely realistic.

	-hpa

Re: [RFC PATCH] x86: don't compile with gcc-3.3.3

[H. Peter Anvin]

On 09/13/2010 09:33 AM, Russell King - ARM Linux wrote:
>>
>> Does it in fact still build with 3.4? I seem to recall some talk about
>> pushing the minimum version to 4.x for x86, although I can't remember
>> where..
> 
> I'm still building kernels with gcc 3.4.3 (for the ARMs which don't
> require a later compiler) or gcc 4.3.2+patches for those which do.
> 
> ARM gcc 3.4.3 is certainly noticably faster than gcc 4.3.2 even on
> x86 - and as long as ARM gcc 3.4.3 works, and there's not great pain
> in allowing it to build the arch-independent stuff, I see no reason
> to deny it across the entire kernel build.
> 
> I think we should have a minimum compiler version for the generic
> kernel, and individual minimum compiler versions for the architectures,
> so that arches can specify a higher minimum compiler version if they
> have specific problems there.

Yes, I don't think anyone has proposed bumping past 3.4 for the generic
kernel at this time.

	-hpa

Re: [RFC PATCH] x86: don't compile with gcc-3.3.3

[Florian Mickler]

On Mon, 13 Sep 2010 10:25:43 -0700
"H. Peter Anvin" <hpa@zytor.com> wrote:

> On 09/13/2010 09:28 AM, Florian Mickler wrote:
> > 
> > What about issuing a warning like 
> > 
> > "gcc 3.3.3 is broken because of bug [bugdescription/url].
> > if you know your build is not affected by this bug do:
> > touch .gcc333bugfixNNNN but please be aware that you are 
> > not supported by the mainline kernel development comunity 
> > if you do"
> > 
> > and implementing the accompanying logic?
> > 
> 
> URK.
> 
> The workload of maintaining that crap would be astonishing, especially
> for something at the tail end of supportable.
> 
> I don't think that is even remotely realistic.
> 
> 	-hpa

I can imagine that even without having expirienced anything alike :) 

Should I then resend this RFC-Patch updated to abort the x86-build for
gcc -lt 3.4?

Regards,
Flo

Re: [RFC PATCH] x86: don't compile with gcc-3.3.3

[H. Peter Anvin]

On 09/13/2010 11:42 AM, Florian Mickler wrote:
> 
> I can imagine that even without having expirienced anything alike :) 
> 
> Should I then resend this RFC-Patch updated to abort the x86-build for
> gcc -lt 3.4?
> 

I'm doing a patch series which is a little more complete; I'll post it
shortly.

	-hpa

Re: [RFC PATCH] x86: don't compile with gcc-3.3.3

[Florian Mickler]

On Mon, 13 Sep 2010 13:00:57 -0700
"H. Peter Anvin" <hpa@zytor.com> wrote:

> On 09/13/2010 11:42 AM, Florian Mickler wrote:
> > 
> > I can imagine that even without having expirienced anything alike :) 
> > 
> > Should I then resend this RFC-Patch updated to abort the x86-build for
> > gcc -lt 3.4?
> > 
> 
> I'm doing a patch series which is a little more complete; I'll post it
> shortly.
> 
> 	-hpa

ok, cool. 

Regards,
Flo