The sound triangulated was in cryogenic liquid oxygen at 50 PSI. The speed of sound in that is approximately 1 kilometer per second.This paper is about calculating the exact speed. Elon talked in the conference about reading telemetry with millisecond accuracy. But this would yield only 1 meter resolution.

That's not the way it works. When cross-compiling, configure runs on the host. It tests that things compile. It doesn't test that they run.

Roger,

This is great. It does look like a 1:1 mapping to what we expect autoconf to do, except neater and maintainable.

The only problem with selling this to GNU folks is that it would make CMake a prerequisite to everything. But I think it's worth it. And then there's inertia. And the language isn't as pretty as we'd like.

Can you see any other possible objections?

Thanks

Bruce

Cmake are scons require that they already be installed.

This is assuming that a shell capable of running ./configure is available on all of your platforms.

I should correct that: automake builds things by creating makefiles. The configure script created by autoconf is concerned with configuration rather than building, but its output is input to automake.

CMake, Scons, etc. are mainly targeted at dependency-based building of programs. Autotools doesn't really build anything. It goes through a long list of system facilities, determining if each is present. For many, perhaps most of them, it builds a little C program that exercises the facility, and sees if it compiles.

Now, there's another poster who says you really can do this with CMake, which I'll have to look at.

This isn't really a problem for StackOverflow. It's a problem for the developers of GCC and its libraries, and a policy problem for the overall GNU project in that Autotools is IMO too much of a mess to live, and is a barrier to participation as it stands. That's why I talk about it here instead of just submitting it as a bug report.

I would like to see someone come up with an alternative. That alternative is not CMake or Scons, etc., because those are build systems rather than systems that probe a platform for fine differences in the programming environment and produce a set of macro switches as output.

Yes, I can get a pre-built toolchain or a building kit, but it doesn't really solve the problem of not being able to build the current GCC with the right settings in its configure script and to use it with the right C library and kernel headers for my device. Should I modify any of those toolchain kits to do that, they'll come up with the same errors.

Besides devKitARM, there is the collection of toolchains mentioned here. I am getting most of my clues from the Emcraft toolchain, which is the only one for the SmartFusion. And we're great friends with Emcraft, but I want something a bit newer and a different build-tree style.

My last approach to the libstdc++ mailing list, here, was left unanswered. I figured out the problem behind that one, but it would have been nice to get some advice.

Autoconf doesn't have a --synclines flag, but I might be able to pass it in the M4 environment variable. I'll give it a try.

I've been configuring a toolchain for Algoram's programmable radio transceiver, which has a SmartFusion 2 containing a Cortex M3. Until today, I've been working with GCC 5.1. Building GCC for cross-compilation on a no-MMU, no-FP processor and a software platform that doesn't support shared libraries isn't trivial, though it should be. GCC has many configure scripts, one for each library that it builds and at least one for the compiler. You run across many configure issues which are difficult to debug. For example, the configure file, a macro-expanded shell script, doesn't have source code line numbers from its configure.ac file. Error messages do not in general indicate the actual problem, and are difficult to trace. Figuring out what to fix is far from trivial. I ended up not being able to use multilibs (which would have allowed me to build for FP processors like Cortex M4F as well), couldn't link in ISL, couldn't build libjava.

Some of these are beginner problems - I'm new to building cross-toolchains and have avoided autotools as much as possible before this project. But not all of them.

One would think that we could build a better system today than such voluminous M4 and shell. Perhaps basing it on a test framework might be the right approach.

First of all, this is really old news. SpaceShip One no longer flies and has been a museum piece for years, and Virgin's burned their bridges with Scaled Composites and thus made it a lot less likely that they will be able to mount a near space effort with the SpaceShip Two design.

Second, this is not an orbital re-entry system, because it's not well-suited for a heat shield and thus can't do the necessary atmospheric braking. It's just a system to get you back from high altitude suborbital flights.

Wrong. Advertisement works, that is why it's a billion dollar industry. You think you don't read billboards and ignore other ads? Think again. Your brain picks them up long before it even tells your conscious mind about it. Filtering it out is an intentional process that takes effort (tiny, but effort). And images and emotions are processed by your mind if you want it or not.

No, it is not.

Advertisement created this idea of free services being paid by advertisement. There was a different time in this world, when you paid for your newspaper at the kiosk, and if you wanted to have a website for your journal, you would pay a hosting company.

There were also shared-cost services long before things became commerzialised. Back in FIDOnet days, email was transported by phone lines, and a bunch of people would come together, one of them set up a small server that would do the long-distance delivery and the others would pay him a buck or two a month to cover his phone bills while they got their mail for free or very cheap at local rates.

There is no reason that Facebook could not charge for its service. Except that the advertisement industry has created the concept of everything being free. Nowadays, having a pay service is not viable, not for any sane reasons, but simply because of this parlour trick.

Radio and TV in the time when they were sent by radio waves (and not digitally via cable) are about the only things where there are actual technical reasons why a pay service is not going to work. You can use encryption, but in pre-ubiquituous-computing times, it dramatically raises costs for new customers who need a hardware box.

But those times are over. Today, I challenge you to name one service that for technical or other reasons that were not artificially created (i.e. the expectation of customers that it should be free) has to use advertisement. I don't think you can. Everything that can be monetized by advertisement could be monetized in other ways.
The "there are no alternatives" claim is a damned lie, in politics as well as in business.

Not really, no. He's just saying what I've been thinking (and saying, but since I'm not a reknown philosopher, few listen) for many years.

If you know anything at all about the mind and the brain, you understand that attention isn't free. That even "filtering out" advertisement (and we don't really, we just consume it unconsciously) takes up valuable mind-effort. That living in a city is stressful in parts because our brains are constantly busy, busy, busy with the environment, running a million-year-old program that constantly scans the area for potential threats or mates, and advertisement intentionally triggers those subroutines all the time (why do you think "sex sells"?).

Advertisement is a massive drain of resources, and the best thing I've ever done for myself was to throw out my television and stop listening to the radio. At least the inside of my home is mostly ad-free.