[Qemu-devel] Current state of GCC 4 (non-)"support" on x86-64 ?

[Qemu-devel] Current state of GCC 4 (non-)"support" on x86-64 ?

[Emmanuel Charpentier]

Dear list,

I understand that the current "official" qemu needs gcc 3.x and won't
compile with gcc 4.x

I also understand that using a gcc3-compiled module (kqemu, in the
present case) entails a cgg3-compiled kernel.

I successfully recompiled such a kernel and qemu. So far so good.

However, this annoys me : the distribution I use (Ubuntu amd64) has
switched (foolishly, IMHO) to gcc 4 for its' "native" kernels ... and
proprietary kernel modules packages.

Since using those proprietary modules (for video, etc ...) give a *huge*
performance boost to my poor laptop, I'd rather use them for the time
being. And since rebuilding those packages is (apparently) a $h!+load of
work, I'd rather patch qemu sources and use a "native" kernel...

Paul Brooks posted on May 12 a patch allowing compilation of qemu on a
X86-64 host with GCC4. However, he didn't mention the use of gcc 4 for
kqemu generation.

So the question is :
Does Pa	ul's patch allow for successful compilation of qemu and kqemu
with GCC 4, at least on X86-64 ?

Thank you for your answers and comments !

					Emmanuel Charpentier

Re: [Qemu-devel] Current state of GCC 4 (non-)"support" on x86-64 ?

[Paul Brook]

On Friday 30 September 2005 16:59, Emmanuel Charpentier wrote:
> Dear list,
>
> I understand that the current "official" qemu needs gcc 3.x and won't
> compile with gcc 4.x

You can compile qemu and the kernel module with different compilers.

Paul

Re: [Qemu-devel] Current state of GCC 4 (non-)"support" on x86-64 ?

[Jim C. Brown]

On Fri, Sep 30, 2005 at 05:18:02PM +0100, Paul Brook wrote:
> On Friday 30 September 2005 16:59, Emmanuel Charpentier wrote:
> > Dear list,
> >
> > I understand that the current "official" qemu needs gcc 3.x and won't
> > compile with gcc 4.x
> 
> You can compile qemu and the kernel module with different compilers.
> 
> Paul
> 

To clarify: Just use gcc 4.x for kqemu, and load that into ur gcc 4.x kernel.

Use gcc 3.x to build qemu itself (/usr/bin/qemu, /usr/bin/qemu-i386, etc).

-- 
Infinite complexity begets infinite beauty.
Infinite precision begets infinite perfection.

Re: [Qemu-devel] Current state of GCC 4 (non-)"support" on x86-64 ?

[Henrik Nordstrom]

On Fri, 30 Sep 2005, Emmanuel Charpentier wrote:

> I understand that the current "official" qemu needs gcc 3.x and won't
> compile with gcc 4.x
>
> I also understand that using a gcc3-compiled module (kqemu, in the
> present case) entails a cgg3-compiled kernel.

You can compile kqemu with gcc4 even if qemu needs to be compiled with 
gcc3.

Regards
Henrik

[Qemu-devel] Re: Current state of GCC 4 (non-)"support" on x86-64 ?

[Michel Pelletier]

A copule others on this thread mentioned that you can compile the kqemu 
module with gcc 4 and the rest of qemu with gcc 3.x.  Did this work for 
you?  Did it create a performance boost?

I'm asking because I just got qemu working on my ubuntu AMD64 and it 
took me a bit of tinkering to figure out the gcc 4/3.4 issue. 
Eventually I compiled it all, including kqemu, with gcc 3.4 and it all 
works great!  The 3.4 compiled kernel module worked fine with the 4 
compiled kernel.

QEMU is really fast!  I fooled one of my friend into thinking that I was 
actually running a native windows XP.  Is it that much more worth it to 
complile kqemu with gcc 4?

Thank you QEMU developers!  I'm keeping QEMU under my tool belt from now 
on.  Something I'd like to research, is there any possibility, or has 
anyone else considered the possibility to do 1280x800 widescreen (or 
other widescreen resolutions)?

-Michel

Emmanuel Charpentier wrote:
> Dear list,
> 
> I understand that the current "official" qemu needs gcc 3.x and won't
> compile with gcc 4.x
> 
> I also understand that using a gcc3-compiled module (kqemu, in the
> present case) entails a cgg3-compiled kernel.
> 
> I successfully recompiled such a kernel and qemu. So far so good.
> 
> However, this annoys me : the distribution I use (Ubuntu amd64) has
> switched (foolishly, IMHO) to gcc 4 for its' "native" kernels ... and
> proprietary kernel modules packages.
> 
> Since using those proprietary modules (for video, etc ...) give a *huge*
> performance boost to my poor laptop, I'd rather use them for the time
> being. And since rebuilding those packages is (apparently) a $h!+load of
> work, I'd rather patch qemu sources and use a "native" kernel...
> 
> Paul Brooks posted on May 12 a patch allowing compilation of qemu on a
> X86-64 host with GCC4. However, he didn't mention the use of gcc 4 for
> kqemu generation.
> 
> So the question is :
> Does Pa	ul's patch allow for successful compilation of qemu and kqemu
> with GCC 4, at least on X86-64 ?
> 
> Thank you for your answers and comments !
> 
> 					Emmanuel Charpentier

Re: [Qemu-devel] Re: Current state of GCC 4 (non-)"support" on x86-64 ?

[Gwenole Beauchesne]

On Sun, 9 Oct 2005, Michel Pelletier wrote:

> A copule others on this thread mentioned that you can compile the kqemu 
> module with gcc 4 and the rest of qemu with gcc 3.x.  Did this work for 
> you?  Did it create a performance boost?

I don't think you'd gain much since most of the time is spent in generated 
code and synthetic opcodes are similarly generated from gcc3.4 and gcc4.

Paul Brook posted an on-going effort to replace dyngen with a hand-written 
code generator that doesn't depend on specific compiler behavior.

BTW, qemu also builds on x86_64 with gcc4 and some patches he posted 
earlier too.