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.

I'd also hypothesize just lack of familiarity with some of the common scams, due to not being involved in a community or social setting where you'd run across them and learn about them. I recognize typical internet scams because I grew up on the internet and spend a lot of time there. At a glance I can recognize a lot of scams and even tell you which ones they are (many have names). My parents have more difficulty detecting obvious internet scams, and when they do it usually takes them more effort. They have to actually think through what might be going on, what the motivations would be, etc., whereas I recognize them by pattern-matching.

It's the other way around, all else being equal, right-handed pitching is generally better in baseball. Whereas left-handed batting is better. The reason is that batters tend to do better against a pitcher of the opposite handedness, since they have a better angle on the ball. And most players are right-handed, so it's generally better to pitch right and bat left. Left-handed pitchers do have some advantages, such as easier pick-off throws to first base, but the disadvantage of pitching mostly against opposite-handed batters.

The original version of the "temporary worker program" was passed in 1952, and it's been continually revised over the years, in the direction of expanding it mostly. Some history here. The current version of the program dates to 1990, in legislation that was passed by a Democratic congress and signed by a Republican president.

But history aside, is there a meaningful partisan divide on this issue? My impression is that when it comes to actual legislative action, both parties have been mostly in favor of the program. There is opposition in both parties as well, in the Republicans mainly from the anti-immigration faction, and in the Democrats mainly from the union faction. But not enough opposition to do much about it.