On 2/21/10, Dave Korn <dave.korn.cyg...@googlemail.com> wrote: > On 21/02/2010 20:03, Martin Guy wrote: > > The point about defaults is that the GCC default tends to filter down > > into the default for distributions; > I'd find it surprising if that was really the way it happens; don't > distributions make deliberate and conscious decisions about binary standards > and things like that?
Changing the default without losing that compatability would assume that every distro (and there are hundreds of them) either already specifies a specific arch or that its GCC maintainer notices the change in GCC and adds explicit configuration options to revert the change. The big ones with dedicated maintainers for GCC probably already do that; others just configure and make the standard distro and take what comes. On 2/21/10, H.J. Lu <hjl.to...@gmail.com> wrote: > There is nothing which stops them from using -march=i386. It just may not > be the default. There is: the arch that the libraries in their distro were compiled to run on. On 2/21/10, Steven Bosscher <stevenb....@gmail.com> wrote: > On Sun, Feb 21, 2010 at 9:22 PM, Erik Trulsson <ertr1...@student.uu.se> wrote: > > One of the great advantages of much free/open software is the way it > > will work just fine even on older hardware. > And, let's face it, most users of gcc don't use it because it is free > software but because it performs just fine for them. And when it does > not, they just as easily switch to another compiler. Hardly. At present there is a GCC monoculture, both in what is the standard compiler with most systems and in what compiler packages will build with, either because the build system uses GCC-specific flags or because the code using GCC extensions. On 2/21/10, Steven Bosscher <stevenb....@gmail.com> wrote: > Which brings us back to the discussion of satisfying the needs of a > tiny minority while hurting the vast majority of users. There's a difference in quality between the two. The "hurt" is that powerful modern PCs might take 20% longer to encode a DVD, while the "needs" is that the bulk of software will run at all on their poor hardware. It's usual in modern societies to give priority to enabling the underprivileged to function at all over giving the well-off the maximum of comfort and speed, but how you value the two aspects probably depends on your personal experience of the two realities. On 2/21/10, Dave Korn <dave.korn.cyg...@googlemail.com> wrote: > On 21/02/2010 21:53, Steven Bosscher wrote: > > Yes, of course -- but what is the advantage of using the latest GCC > > for such an older processor? > Tree-SSA? LTO? Fixed bugs? New languages? Etc? I can see plenty of good > reasons for it. Apart from those factors (and one hopes that in general all code generation improves from release to release), users may not really have a choice, being most likely to try (or be given) the most recent stable version of whatever distro, and distros tend to try to ship the most recent stable gcc in each new release. Let me add another example from my own experience: In 2001 I was stuck for months in a crumbling house in the countryside with nothing but an 8MB 25MHz 386 because that's all l I had available at the time (green screen, yay!) and I completed what would have been my postgraduate degree project, begun in 1985: an unlimited precision floating point math library in a pure functional language. The fact that I could do that at all may be due to GCC's "work on the minimum" policy of the time, both in the distro and on whatever machine David Turner used to compile the binary-only release of the Miranda interpreter. If I recall correctly, the default is currently arched and tuned for 486, and the 386's lacks are trapped and emulated in the kernel. On 2/21/10, Steven Bosscher <stevenb....@gmail.com> wrote: > Well, as Martin already pointed out (contradicting his own point): > Apparently a lot of distributions *do* change the defaults. That's OK, I don't have The Truth in my pocket. Nor do I have any quantifiable measure of the number of different systems in use in the whole world, just a value judgement based on a different set of experiences of the outcome of restrictive and generous policies in munimum CPU targetting, which I'm sharing. My direct experience is that low-end PCs are widely used in societies where things are hard, and that upstream software developers are always given the latest, fastest computers to make them more productive and are unaware of the struggling masses :) Cheers M
