On Fri, 30 Sep 2011 14:35:57 +0200
Chris Jones <
chris@martin-jones.com> wrote:
> Hi all,
>
> I hope the cross-development gurus out there might have a simple answer
> to this question. Basically I've got an application here which I'd like
> to cross-build to run on a Balloon board.
Yes, when time allows, I need to update the docs on the Emdebian wiki
about this. The issue is that the entire cross-build setup in Debian is
in flux, pending the arrival of MultiArch. In the meantime, apt-cross
became so broken by other changes, that it had to be removed. xapt is
the interim solution. If you are using Lenny, then apt-cross still
works. If you are using Squeeze, you need xapt. When Wheezy comes
around, the expectation is that there will be "the final solution",
based on MultiArch.
> It has worked before, and
> indeed cross-builds quite happily on another machine, but on the Debian
> Squeeze box I've got set up here, fails because it can't find a header
> file in /include/libssl.
That actual path (or partial path) doesn't exist in Debian, native or
cross. What I think you need is include/openssl/ which is part of the
libssl-dev package. Once processed with xapt, this becomes:
/usr/arm-linux-gnueabi/include/openssl/
The other possibility is that the package itself has been updated (the
version in Squeeze is almost certainly different) and that version might
not actually be cross-buildable at that version. Linaro are doing some
cross-builds but whether this package is involved, I have no idea.
Wookey?
> Looking at the machine which works, the offending file is present and
> correct.
To be correct, it needs to be in /usr/arm-linux-gnueabi/include/
Anything in /usr/include is the build architecture, not the host
architecture. (BuilD = Desktop, Host = handheld so build is i386 or
amd64 usually, host is armel or armhf.)
The header files themselves are often architecture-independent but the
library against which the compiled code is linked must be the correct
architecture and that needs to be in /usr/arm-linux-gnueabi/lib/ and is
usually brought in as a dependency of the -dev package.
Depends: libssl0.9.8-armel-cross (= 0.9.8o-4squeeze2)
So libssl0.9.8-armel-cross contains the libraries against which the
compiled code will be linked:
/usr/arm-linux-gnueabi/lib/libssl.so.0.9.8
> According to dpkg -S, it's owned by libssl-dev-armel-cross. But
> I can't figure out how to install that package.
If dpkg -S says that the file is owned by that package, that can only
be because the package IS installed.
Check with:
dpkg -l libssl-dev-armel-cross
If the package you are trying to cross-build cannot find it, the
problem is going to be in the package itself not correctly identifying
that it is actually doing a cross build.
If the cross package is too old, a specific file might not be found but
the directory probably hasn't changed.
> All the internet
> searching I've done has pointed to using apt-cross, but that seems to
> have gone away in Debian Squeeze.
Yes, the alternative is xapt but it is NOT a drop-in replacement
because apt-cross was just too broken to be replaced in that way.
> What's the approved way of installing -dev package for cross-building
> under Debian at the moment?
$ sudo apt-get install xapt
$ sudo xapt -m -a armel libssl-dev
The BIG change from apt-cross is that xapt NEVER tries to work out what
is currently installed as -cross packages, it simply downloads
everything, crosses everything (including stuff which doesn't need to
be crossed) and installs everything, old or new. It's blind, it's dumb
but it doesn't get confused and it doesn't try to be clever.
The -m switch is because some of the packages are part of the way
through conversion to MultiArch.
However, as dpkg -S knows about the file that can only mean that the
-cross package is already installed. You need to check that first and
work out what is going wrong there before assuming that the package is
not installed.
Alternatively, build it natively on a faster armel box...
--
Neil Williams
=============
http://www.linux.codehelp.co.uk/
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