[ntp:questions] Help with cross-compiling NTP for the Raspberry Pi requested

Brian Inglis Brian.Inglis at SystematicSw.ab.ca
Sat Mar 8 06:46:40 UTC 2014

On 2014-03-07 13:42, David Taylor wrote:
> On 07/03/2014 18:10, Charles Swiger wrote:
>> Hi--
>> On Mar 7, 2014, at 7:30 AM, David Taylor <david-taylor at blueyonder.co.uk.invalid> wrote:
>> [ ... ]
>>> No, still getting an ntpd which is 2.87 MB in size, whereas on the Raspberry Pi native build it's 2.0 MB.  The Intel Debian version is 2.74 MB.
>> Run 'file ntpd' to see which architecture it's compiled for.  (The size of ntpd is not especially relevant...)
>> Regards,
> Thanks, Chuck.  That's interesting - I get:
> ntpd: ELF 64-bit LSB executable, x86-64, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.26, BuildID[sha1]=0x0ab8a3efbd066aa259e20d9abedbe4d1a0d1d1ba, not stripped
> So if I read that correctly, I have ended up with a 64-bit Intel version instead of a 32-bit ARM version.  I was using the file size in the expectation that if a cross-compile had worked, the executable should have been quite similar in size to a native build.

That you are getting an Intel build shows you are not cross-compiling.
You should be able to check what you are building on by looking under
/usr/lib/gcc/, but that may depend on your distributions: use .../...gcc -v and
check what they say after --host=, --target, --*prefix, and --...dir=.
All gcc distributions (and) can/should be configured and installed under the
same base dirs differing only in their host/target triple subdirectory.
Your cross-compiler will probably be built with --build==--host and

You may also have different binutils under e.g. /usr/<prefix>/bin to handle
different object file format variations, and that dir may also need to be
added to your path, if not installed in standard gcc  dir locations.

With your current setup, looks like you should be running configure as:
./configure --build=x86_64-unknown-linux --host=arm-bcm2708hardfp-linux-gnueabi --target=arm-bcm2708hardfp-linux-gnueabi\ --enable-linux-caps
but -unknown- could be -pc-, and you may also need a different binutils dir
at the head of the path.

(Re-)read the environment/cross-compiling notes for gcc and autoconf
(type info gcc and info autoconf and look for environment and targets)
to ensure you have everything required available in the right places,
and have modified what the configure and make processes require to

Shell scripts are your friends for this because you can reproduce
and reverse whatever you need to do to setup your cross-environment,
within the shell child environment, without breaking your normal
Linux shell environment.

You may need to do something like create an RPi-cross-bin directory,
symlink cross-compiler components into that ...bin using their normal
names, without any cross-compile prefix, then add that ...bin directory
to the head of your path while you are cross-configuring and compiling,
so that autoconf and gcc get to see what they expect to see, if the NTP
setup requires tweaks to cross-compile.

You may want to first try copying over all the configure generated
files from the native RPi build, modify those and/or the environment,
and try make.

You could also try backing up your Linux cross-compile directories
to another set of directories, and also copy across your whole
native RPi compiler environment to a different set of directories,
and diff both sets of include, SO, and lib directory contents
to check for any differences between your cross- and native RPi
compiler environments.

You could then try to cp -f the contents of your native RPi compiler
include, SO, and lib directory contents over the relevant cross-compiler
environment directories, excluding of course the native Linux cross-compiler
(and perhaps binutils) executables, SOs, and libs.
This should ensure that the cross- and native RPi compilers are working
with the same source and object libraries you have on your RPi.

When you have managed a cross-configure, diff the generated files
against those from your native RPi configure, to see if there is
anything you may need to tweak, before you cross-make anything.

Take care. Thanks, Brian Inglis

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