613173 - We incorrectly use $target instead of $host

Status: RESOLVED FIXED

(Firefox Build System :: General, defect)

Description

[Paul Biggar]

From my reading of the autotools book [http://sources.redhat.com/autobook/autobook/autobook_258.html] (which I imagine is stull current because we use autoconf 2.13), we should be cross-compiling using $host, not $target. $target is for tools that generate code, like a compiler, which Mozilla is not. $host is for the system that the compiled binary will run on, which is what we want.

So for example, in configure.in, we check $host != $target, which should always be false if we used the tools correctly. Instead, we set |./configure --target|, and luck out that it works out OK.

By contrast, when configuring js/src/libffi (from js/src/configure.in) we set $build and $host (ie we do it correctly). It seems this hasn't caused us trouble, but I'm not positive why since it shares the config.cache with higher-level build steps.

Comment 1

[Benjamin Smedberg]

We misuse $host to mean $build and $target to mean $host. But we've done this for so long that changing it now would be pretty confusing to people. We've talked about adding a set of shims so that when people set --target=foo they actually mean --host=foo and changing the HOST_*FLAGS to be BUILD_*FLAGS, but the risk is high and the win is fairly low.

We should probably refactor the configure script first, at least.

Comment 2

[(not currently active) Ted Mielczarek]

see bug 475488 comment 6.

Comment 3

[Paul Biggar]

Attachment: Comment describing the $host/$target weirdness

OK, how do we feel about this patch? (I'll backport it to configure.in fomr js/src/configure.in if the tree ever opens again).

Comment 4

[(not currently active) Ted Mielczarek]

I don't think a comment in configure is going to be all that useful, is it?

Comment 5

[Paul Biggar]

(In reply to comment #4)
> I don't think a comment in configure is going to be all that useful, is it?

Better than no comment about this.

Unless you mean that it should go in the |configure --help| output?

Comment 6

[(not currently active) Ted Mielczarek]

Comment on attachment 491591 [details] [diff] [review]
Comment describing the $host/$target weirdness

It's harmless, so I don't oppose it, I just don't think anyone is going to read our configure.in to find it if they actually hit this confusion.

Comment 7

[Paul Biggar]

http://hg.mozilla.org/tracemonkey/rev/870bb8ee43e6

Comment 8

[Robert Sayre]

http://hg.mozilla.org/mozilla-central/rev/870bb8ee43e6