[Interest] Qt Binaries for Mingw 4.7

K. Frank kfrank29.c at gmail.com
Mon Jul 23 23:24:38 CEST 2012

Hello Konrad!

On Mon, Jul 23, 2012 at 4:33 PM, Konrad Rosenbaum <konrad at silmor.de> wrote:
> Hi,
> ...
>> Do I take it correctly that you've managed a g++ 4.7 windows build
>> (i.e., mingw) of Qt?  Is it working?
> Yes, I was able to confirm that it is working.

Well, that's good.  (Sometimes effort pays off.)

> ...
> Doubtful. The only way to do this would be to add buffering and prefetching to
> mingw implementations of read, write, open, close, etc. This would break some
> of the promises they make - i.e. that they are synchronous in regard to all
> other processes on the same machine.

Well, that's too bad.  I wonder how microsoft does it.  (My
understanding is that the msvc compile times are pretty good.)

> But I could imagine that slipping a layer between mingw and gcc could help,
> since those promises don't need to be quite as strong in the typical GCC
> scenario (it is enough to be synchronized after the gcc process ends).
> Hmm, is there an equivalent to LD_PRELOAD on Windows? I.e. is it possible to
> exchange certain library calls for some processes, but not others?

Thanks for the suggestions.

> ...
>> I should note that when I upgraded to g++ 4.7.0 and Qt 4.8.0-rc1,
>> I almost didn't have enough memory to complete the build.  The
>> build process ran out of memory when linking QtGuid4.dll, but
>> after a fresh reboot and killing off what I deemed to be some
>> unnecessary processes (to free up as much memory as I could),
>> I was able to rerun the build process and have it complete successfully.
>> (At that time people made various suggestions as how to reduce
>> the memory requirements of the build.  But since I ended up having
>> enough memory, I didn't try any of them, and I did successfully
>> complete the default build.)
> Out of curiosity: how much memory did it take? I usually give my Windows-VM
> less than 1GB.

I don't know exactly.  I would say that I needed pretty close to 2 GB
(not just for the linking process itself, but also for whatever else the
os felt it needed.)

My reasoning is that I have 2 GB of physical memory.  I tired the
build after my machine had been running for a while, and with some
irrelevant processes running, and the build failed.  I then rebooted,
and killed of what I thought were extraneous processes, and the
build succeeded.

If I had to guess, I would guess that the build needed somewhere
between 1.5 and 2 GB, but that's just a soft guess.

I don't know to what extent the memory you assign your VM and
the physical memory on my machine are comparable, and I don't
know what effects my using 64-it windows has, but based on my
experience, I'm not surprised that your build failed with out of memory
if you gave it less than 1 GB.

> ...
>         Konrad

Happy Qt Hacking!

K. Frank

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