Re : [Qemu-devel] WE NEED GCC 4 please

Re : [Qemu-devel] WE NEED GCC 4 please

[Sylvain Petreolle]

I think you  dont answer his question. ;)
 

Kind regards,

Sylvain Petreolle (aka Usurp)


----- Message d'origine ----

De : Jérôme PRIOR <ast3roid@gmail.com>

À : qemu-devel@nongnu.org

Envoyé le : Dimanche, 20 Janvier 2008, 19h40mn 29s

Objet : Re: [Qemu-devel] WE NEED GCC 4 please



> could you please consider supporting gcc 4 ?



you can install gcc-3 in other directory and use the --cc= option.



On Slackware I just

 installpkg -root /tmp/gcc3-just-for-qemu gcc-3*tgz

 ./configure --cc=/tmp/gcc3-just-for-qemu/usr/bin/gcc

  make

  ...



works fine.

Re: [Qemu-devel] WE NEED GCC 4 please

[Mike Frysinger]

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On Sunday 20 January 2008, Sylvain Petreolle wrote:
> I think you  dont answer his question. ;)

his question is bogus.  if he spent 5 seconds reading the archives, it isnt 
like people arent "considering supporting gcc 4".  having people type all 
caps e-mails contributes nothing.  either put up and assist the effort or 
shut it.
-mike

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Re: [Qemu-devel] WE NEED GCC 4 please

[Johannes Schindelin]

Hi,

On Sun, 20 Jan 2008, Mike Frysinger wrote:

> having people type all caps e-mails contributes nothing.

I disagree: it makes it easier to spot whom to ignore.  Unless you know 
that person, of course, and respect her, too.

Ciao,
Dscho

Re: [Qemu-devel] WE NEED GCC 4 please

[Mike Frysinger]

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On Sunday 20 January 2008, Johannes Schindelin wrote:
> On Sun, 20 Jan 2008, Mike Frysinger wrote:
> > having people type all caps e-mails contributes nothing.
>
> I disagree: it makes it easier to spot whom to ignore.  Unless you know
> that person, of course, and respect her, too.

yes, the caps flags people to ignore, but that isnt what i meant.  people who 
write all caps e-mails contribute nothing to the problem they're complaining 
about.
-mike

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Re: [Qemu-devel] WE NEED GCC 4 please

[Sunil Amitkumar Janki]

On Jan 20, 2008 11:26 PM, Mike Frysinger <vapier@gentoo.org> wrote:
>
> On Sunday 20 January 2008, Johannes Schindelin wrote:
> > On Sun, 20 Jan 2008, Mike Frysinger wrote:
> > > having people type all caps e-mails contributes nothing.
> >
> > I disagree: it makes it easier to spot whom to ignore.  Unless you know
> > that person, of course, and respect her, too.
>
> yes, the caps flags people to ignore, but that isnt what i meant.  people who
> write all caps e-mails contribute nothing to the problem they're complaining
> about.
> -mike
>

Ignoring the fact that the original poster wrote in all caps and can't
contribute much to qemu development, what is being done or who can
give directions on what would have to be done to make qemu build using
gcc4. I'd prefer it too that I wouldn't have to keep an old gcc 3.x
compiler around specifically to build qemu, so what can we do about
that?

Sunil

Re: [Qemu-devel] WE NEED GCC 4 please

[Mike Frysinger]

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On Sunday 20 January 2008, Sunil Amitkumar Janki wrote:
> Ignoring the fact that the original poster wrote in all caps and can't
> contribute much to qemu development, what is being done or who can
> give directions on what would have to be done to make qemu build using
> gcc4. I'd prefer it too that I wouldn't have to keep an old gcc 3.x
> compiler around specifically to build qemu, so what can we do about
> that?

as i said, review the archives and you'll find many discussions with real 
information on the topic
-mike

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Re: [Qemu-devel] WE NEED GCC 4 please

[Philip Boulain]

On 20 Jan 2008, at 22:56, Mike Frysinger wrote:
> On Sunday 20 January 2008, Sunil Amitkumar Janki wrote:
>> ...what is being done or who can
>> give directions on what would have to be done to make qemu build  
>> using
>> gcc4.
> as i said, review the archives and you'll find many discussions  
> with real
> information on the topic

http://lists.gnu.org/archive/html/qemu-devel/2008-01/msg00380.html

Work forward (by date) from here.

Now please stop this pointless thread. *Useful* gcc4 discussion  
belongs in critique of those patches. (Thanks to Alex et. al., while  
I'm posting---hopefully this'll be a great boon for getting Q (kju)  
to build against SVN qemu some day soon!)

LionsPhil

Re: [Qemu-devel] WE NEED GCC 4 please

[Andreas Färber]

Am 20.01.2008 um 23:38 schrieb Sunil Amitkumar Janki:

> Ignoring the fact that the original poster wrote in all caps and can't
> contribute much to qemu development, what is being done or who can
> give directions on what would have to be done to make qemu build using
> gcc4. I'd prefer it too that I wouldn't have to keep an old gcc 3.x
> compiler around specifically to build qemu, so what can we do about
> that?

I have some more reading to catch up but the last I heard was that  
virtually everything worked except for gcc 4.3 and MinGW 3.4.2 and in  
my case sh4*-softmmu on OSX/ppc gcc 4.0.1...
What to do about any of that I don't know either.

Andreas

Re: [Qemu-devel] WE NEED GCC 4 please

[Johannes Schindelin]

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Hi,

On Sun, 20 Jan 2008, Andreas Färber wrote:

> Am 20.01.2008 um 23:38 schrieb Sunil Amitkumar Janki:
> 
> > Ignoring the fact that the original poster wrote in all caps and can't 
> > contribute much to qemu development, what is being done or who can 
> > give directions on what would have to be done to make qemu build using 
> > gcc4. I'd prefer it too that I wouldn't have to keep an old gcc 3.x 
> > compiler around specifically to build qemu, so what can we do about 
> > that?
> 
> I have some more reading to catch up but the last I heard was that 
> virtually everything worked except for gcc 4.3 and MinGW 3.4.2 and in my 
> case sh4*-softmmu on OSX/ppc gcc 4.0.1... What to do about any of that I 
> don't know either.

All of sh4-*, in fact.

I plan to work around the MinGW issue by guarding the offending part by 
"#ifdef GCC...", even if I have been told that it works only by chance 
(but it works, whereas any other option I tried does not).

Ciao,
Dscho

Re: [Qemu-devel] WE NEED GCC 4 please

[Mulyadi Santosa]

Hi...

If I may jump into the pool...

> I plan to work around the MinGW issue by guarding the offending part by
> "#ifdef GCC...", even if I have been told that it works only by chance
> (but it works, whereas any other option I tried does not).

Ehm, should we better wait a bit for fabrice to complete his code code
generator? then we can be freed (totally?) from gcc version
dependency? it's not that I ignore people's effort to make qemu gcc4
compatible...but I just think it will save us from more work in the
future (making it always gcc 3 compatible) and thus progress to more
demanding area like truly support SVM/VT,  better SMP and so on.

just 2 cents opinion...

regards,

Mulyadi.

Re: [Qemu-devel] WE NEED GCC 4 please

[Alexander Graf]

On Jan 21, 2008, at 4:39 AM, Mulyadi Santosa wrote:

> Hi...
>
> If I may jump into the pool...
>
>> I plan to work around the MinGW issue by guarding the offending  
>> part by
>> "#ifdef GCC...", even if I have been told that it works only by  
>> chance
>> (but it works, whereas any other option I tried does not).
>
> Ehm, should we better wait a bit for fabrice to complete his code code
> generator? then we can be freed (totally?) from gcc version
> dependency? it's not that I ignore people's effort to make qemu gcc4
> compatible...but I just think it will save us from more work in the
> future (making it always gcc 3 compatible) and thus progress to more
> demanding area like truly support SVM/VT,  better SMP and so on.

Fabrice's code generator works for x86 and x86_64 only. In the second  
step it _will_ break existing miniops, so all the work put into those  
will be in vain.

I really don't see any valid point not to implement code that makes  
everything work for gcc4 if it doesn't break existing setups. Actually  
everyone benefits if there are alternatives. Imagine you could use  
qemu with gcc3, gcc4 or Fabrice's new approach (probably tcc). This  
way nobody needs to have a specific version of their compiler suite  
installed and ppc, s390 etc. will still be supported.

Support for SVM/VT is something KVM is about. I completely agree that  
qemu and kvm should be merged someday, but if I look at the length of  
discussions and amount of patches actually getting applied to qemu, I  
rather think it's not the right time to do it. You also get full SMP  
support from KVM too, so I don't see any valid point in complaining  
about that in qemu.

Regards,

Alex

Re: [Qemu-devel] WE NEED GCC 4 please

[Johannes Schindelin]

Hi,

On Mon, 21 Jan 2008, Mulyadi Santosa wrote:

> If I may jump into the pool...
> 
> > I plan to work around the MinGW issue by guarding the offending part 
> > by "#ifdef GCC...", even if I have been told that it works only by 
> > chance (but it works, whereas any other option I tried does not).

Thanks for not saying who you quote.

> Ehm, should we better wait a bit for fabrice to complete his code code 
> generator?

I said "work around", didn't I?

And so far I have not seen anything but an announcement that Fabrice will 
start "in the next days".

> but I just think it will save us from more work in the future (making it 
> always gcc 3 compatible) and thus progress to more demanding area like 
> truly support SVM/VT, better SMP and so on.

Most unlikely will it save us more work.

The miniops right now are implemented as plain C commands.  If the "good" 
gcc guys would not have insisted on not having an option to force the 
"ret" or "jmp" statement at the end of the function, we could use them for 
_all_ processors.

As it is, Fabrice's code generator will most likely be something similar 
to Paul's qops, which means that you have to invent a "primitive C" in 
which to write the miniops, and you will have to write a backend for 
_each_ and _every_ host CPU you support.

Things clearer now?

Hth,
Dscho

Re: [Qemu-devel] WE NEED GCC 4 please

[Mulyadi Santosa]

Hi...

On Jan 21, 2008 6:18 PM, Johannes Schindelin <Johannes.Schindelin@gmx.de> wrote:
> As it is, Fabrice's code generator will most likely be something similar
> to Paul's qops, which means that you have to invent a "primitive C" in
> which to write the miniops, and you will have to write a backend for
> _each_ and _every_ host CPU you support.
>
> Things clearer now?

Loud and clear, thanks Johannes :)

regards,

Mulyadi.

Re: [Qemu-devel] WE NEED GCC 4 please

[Andreas Färber]

Am 21.01.2008 um 12:18 schrieb Johannes Schindelin:

> The miniops right now are implemented as plain C commands.  If the  
> "good"
> gcc guys would not have insisted on not having an option to force the
> "ret" or "jmp" statement at the end of the function, we could use  
> them for
> _all_ processors.
>
> As it is, Fabrice's code generator will most likely be something  
> similar
> to Paul's qops, which means that you have to invent a "primitive C" in
> which to write the miniops, and you will have to write a backend for
> _each_ and _every_ host CPU you support.

Has anyone looked into the idea of manually generating machine  
instructions through preprocessor macros at runtime, then jumping  
there? That's what the Mono JIT does, leaving C compilers completely  
out of the picture.

But apart from it being lots of work to start from scratch and for  
each and every host CPU, if translating at instruction level rather  
than method level it would require lots of jumps between instruction  
decoding and generated instructions though.

Andreas

Re: [Qemu-devel] WE NEED GCC 4 please

[Johannes Schindelin]

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Hi,

On Mon, 21 Jan 2008, Andreas Färber wrote:

> Am 21.01.2008 um 12:18 schrieb Johannes Schindelin:
> 
> > The miniops right now are implemented as plain C commands.  If the 
> > "good" gcc guys would not have insisted on not having an option to 
> > force the "ret" or "jmp" statement at the end of the function, we 
> > could use them for _all_ processors.
> > 
> > As it is, Fabrice's code generator will most likely be something 
> > similar to Paul's qops, which means that you have to invent a 
> > "primitive C" in which to write the miniops, and you will have to 
> > write a backend for _each_ and _every_ host CPU you support.
> 
> Has anyone looked into the idea of manually generating machine 
> instructions through preprocessor macros at runtime, then jumping there? 
> That's what the Mono JIT does, leaving C compilers completely out of the 
> picture.

I had looked at GNU lightning briefly (but it only supports x86, SPARC 
and PowerPC), and at LLVM (but it was too complex, and only supports 
JITting for X86, X86-64, PowerPC and PowerPC-64; although they have "An 
easily retargettable code generator, which currently supports X86, X86-64, 
PowerPC, PowerPC-64, ARM, Thumb, SPARC, Alpha, and IA-64.).

Given the unwillingness of Fabrice to rely on some external project, 
though, I gave up even before I had something even rudimentary.

Ciao,
Dscho

Re: [Qemu-devel] WE NEED GCC 4 please

[Julian Seward]

> > > As it is, Fabrice's code generator will most likely be something
> > > similar to Paul's qops, which means that you have to invent a
> > > "primitive C" in which to write the miniops, and you will have to
> > > write a backend for _each_ and _every_ host CPU you support.

It's not a terribly big deal.  Writing backends is a lot easier than
writing front ends, since the back end can just emit some small convenient
subset of target instructions, whereas the front ends have to deal
with every stupid, obscure, weird-ass instruction that ever shows up.

QEMU is not the first project to post-process gcc's output.  The
Glasgow Haskell Compiler
(http://en.wikipedia.org/wiki/Glasgow_Haskell_Compiler)
did that for many years and it was always an immense amount of
hassle tracking the changes to gcc's code generation.  Having a
completely-independent-of-everything, standalone code generator is
definitely a lot easier in the end.

> Given the unwillingness of Fabrice to rely on some external project,
> though, I gave up even before I had something even rudimentary.

Perhaps Fabrice could commit this code generator on a branch, even if
it is not perfect yet.  That would at least provide something "real"
to assess; so far all we have is rumour and speculation.

J

Re: [Qemu-devel] WE NEED GCC 4 please

[Ronan Keryell]

>>>>> On Mon, 21 Jan 2008 11:18:53 +0000 (GMT), Johannes Schindelin <Johannes.Schindelin@gmx.de> said:

    Johannes> The miniops right now are implemented as plain C commands.
    Johannes> If the "good" gcc guys would not have insisted on not having
    Johannes> an option to force the "ret" or "jmp" statement at the end
    Johannes> of the function, we could use them for _all_ processors.

Well, what about adding a new backend phase to gcc generating what we
expect for our purpose? Ok, it is rather easy to have a branch in gcc,
harder to have it accepted in the main-stream gcc... :-) With a good
argumentation...
-- 
  Ronan KERYELL                 |\/  Tel:    (+33|0) 2.29.00.14.15
  Département Informatique      |/)  Fax:    (+33|0) 2.29.00.12.82
  TÉLÉCOM Bretagne, CS 83818    K    GSM:    (+33|0) 6.13.14.37.66
  F-29238 PLOUZANÉ CEDEX 3      |\   E-mail: rk@enstb.org
  FRANCE                        | \  http://enstb.org/~keryell

Re: [Qemu-devel] WE NEED GCC 4 please

[Paul Brook]

> Well, what about adding a new backend phase to gcc generating what we
> expect for our purpose? Ok, it is rather easy to have a branch in gcc,
> harder to have it accepted in the main-stream gcc... :-) With a good
> argumentation...

IMHO (as a full time gcc developer) it's easier to just implement a code 
generator from scratch.

Paul

[Qemu-devel] WE NEED GCC 4 please

[renatogallo]

could you please consider supporting gcc 4 ?

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Re: [Qemu-devel] WE NEED GCC 4 please

[Jérôme PRIOR]

> could you please consider supporting gcc 4 ?

you can install gcc-3 in other directory and use the --cc= option.

On Slackware I just
 installpkg -root /tmp/gcc3-just-for-qemu gcc-3*tgz
 ./configure --cc=/tmp/gcc3-just-for-qemu/usr/bin/gcc
  make
  ...

works fine.