Re: reproducible builds and debugging information

[ludo@gnu.org (Ludovic Courtès)]

Tomáš Čech <sleep_walker@gnu.org> skribis:

> On Tue, Mar 24, 2015 at 10:09:50PM +0100, Ludovic Courtès wrote:

[...]

>>Packages that have an autoconf-based build system, and I suppose most
>>others, are built with -g.
>
> I can't confirm this statement.
>
> I added "debug" output to curl package:

Indeed, I just checked and cURL overrides the default behavior.  Here it
has to be configured with --enable-debug, which also enables the test
suite (!).  Do you want to try that, and add the “debug” output?

>>The binaries get stripped by default and
>>debugging info is lost unless the package has a “debug” output.
>
> OK, the difference -g and -ggdb is slight, but there is the problem
> with "debug" output.
>
> When package has output "debug" always - there is no problem.
>
> When package doesn't have "debug" output and I need it, mere adding
> output "debug" into package receipt will change the hash so I'll get
> different package.

Right.

>>Currently a few key packages have that, but most don’t (I think Debian
>>does something similar, not sure about other distros.)
>
> On openSUSE you have available all the subpackage providing stripped
> debug informations and subpackage providing source code from the
> moment of build (so DWARF information in debug part can match the source).

You mean there’s a ‘-debug’ package for every single package?

>>We could make it opt-out rather than opt-in, but the issue is disk usage
>>on build machine (including end-user machines.)  See
>><http://lists.gnu.org/archive/html/bug-guix/2013-07/msg00015.html>.
>>
>>Thoughts?
>
> If we have distribution of reproducible packages, we can keep it
> opt-in and generate debug information next time (by not dropping
> it).

That’s not how it works; generating the debug info requires redoing the
whole build process, but with a slight difference.

> The only problematic packages will be the big ones like Webkit, Libre
> Office and similar because generating debug increases memory usage
> during the build significantly and may not be suitable for average
> personal computer.

A problem for C++ code in general.

So again, we could make “debug” opt-out by default, but that’ll be some
work because of issues like this.

What do people think?

Thanks,
Ludo’.