On 5 January 2018 at 12:22, Thiago Macieira <[email protected]> wrote: > On Thursday, 4 January 2018 20:52:40 -02 Christian Gagneraud wrote: >> On 5 January 2018 at 03:16, Kevin Kofler <[email protected]> wrote: >> > Thiago Macieira wrote: >> >> In particular: -no-sse2. >> >> >> >> If you use that option, that means you're optimising for Pentium III and >> >> earlier, not Pentium 4. All Pentium 4 processors have SSE2. >> >> I was looking at LEDE (a fork/merge of OpenWRT) recently, and their >> 'i386' build actually target Pentium 4, which is i686++ >> See https://lede-project.org/docs/instructionset/i386_pentium4 > > I don't know what devices LEDE is targetting, but we can break down 32-bit x86 > into four segments:
It's not just about what hardware you target, in my case, i cannot build the codebase in 64 bits, simply because the code is not 64-bits ready (mainly due to legacy old/complicated components): Not only the code base is full of 32 vs 64 issues, but it actually doesn't build at all, and fixing it is not an easy job and not a priority (yet). I wish too, i could target Linux-x86_64, but i cannot. This codebase currently builds for WINTEL32 and Linux/ARM32, it used to be built for a Geode or VIA proc, some time ago, with Qt-4.x And thinking about that, why is it a pain to maintain Linux-x86_32 when you have to maintain Linux-<non-intel>_32 and <non-linux>-*_32? >From http://doc.qt.io/qt-5/supported-platforms.html, Qt-5.10 supports the following 32 bits platforms: - Android-armv7 - WatchOS-armv7 - Windows-{7,8.1,10}-x86_32 - Windows-UWP-{x86_32,armv7} - Boot2Qt-{armv7,x86_32} - Qnx-{armv7,x86_32} Please note the Boot2Qt-x86_32, which is a weird case as it is an "Embedded Linux" for x86_32 (Yocto). The only reason for supporting "Embedded Linux" for x86_32 and not "Desktop Linux" for x86_32 is, I guess, CI workload. > Obviously, my employer would like nothing better than we start targetting 2 > and 3. Those billions of transistors you have in your processor for AVX should > get used to improve performance, not just produce heat. Neatpick: AVX itself doesn't require billions of transistors, the first intel proc to require more than a billion transistor are 4 and 6 cores i7. https://en.wikipedia.org/wiki/Transistor_count This slides are interesting as well, https://www.inf.ethz.ch/personal/markusp/teaching/263-2300-ETH-spring12/slides/class03.pdf. L2/L3 cache is what takes the most space. >> I have been fighting with x86_32 build of Qt too, I never managed to >> build Qt in 32 bits on a 64 bits OS, I always ended up hacking badly >> the host distro (OpenSuse and Ubuntu). I'm now using 32bits OS in a >> docker container. > > I've never had a problem, but I confess I don't try to build all of Qt. I > build all[*] of Qt with GCC and Clang on Linux, but that's 64-bit. The 32-bit > build is only for qtbase, once every couple of months. For example, I still > need to do the benchmarking for the new qHash function in 32-bit, which I find > to be a poor use of my time so I haven't done yet. > [*] not including qtwebengine. I've never built that. You told me so a few month ago, and I switched to OpenSuse since then, but i still had issues, and the only way to get around was to break the host distro (force-install some dev packages, 'ln -sf' SO here and there, ...) Please share your script if you have some. > >> You're not (and I'm not either) the first one to report problems with >> building Qt on x86_32 Linux recently. >> Linux32 is officially not supported any more, and I think it is a mistake. > > Yes, it is. Please report issues so we can fix them. I might do it once i'm back on my 32 bits build task. But the difficulty is to create a "good" ticket. If I do it right now, the issue would look like: "I followed https://wiki.qt.io/Building_Qt_5_from_Git and i cannot build Qt-5.6 for x86_32 on a "common" Linux distro (x86_32/64)" With all due respect to Wiki contributors, https://wiki.qt.io/Building_Qt_5_from_Git looks like a giant mess, with the usual 200 Linux distro specifics, outdated and unorganised information, ... >> Claiming that nobody needs Linux-x86_32 nowadays is plainly wrong. > > Agreed. There are people who need it. Very few, but they exist. What do you base your "very few" on? I would be interested to see the download stats of Qt-5.5 for Linux-32. >> And dropping opensource/commercial Linux-x86_32 support just before Qt-5.6 >> (LTS) was not a user/client friendly move either. > > Since it wasn't dropped, the point is moot. Linux-Desktop-x86_32 was dropped with Qt-5.6. The last Qt version to support it was Qt-5.5, and Qt-5.5 has now disappear from http://download.qt.io/official_releases/qt/ ... Or maybe we're not talking about the same thing. I'm not even sure what the Qt Company means by "Supported until Mar. 16, 2019" on http://doc.qt.io/qt-5.6/supported-platforms.html (that's Qt-5.6). What I'm sure of, is that i cannot download Qt-5.6 binaries for Linux-x86_32 (commercial or opensource). Chris _______________________________________________ Development mailing list [email protected] http://lists.qt-project.org/mailman/listinfo/development
