[Pkg-samba-maint] Bug#971249: Bug#971249: waf: CHECK_VALUEOF does not work during cross compilation

[Andrew Bartlett]

On Fri, 2022-05-06 at 11:40 +0300, Michael Tokarev wrote:
> On Mon, 28 Sep 2020 06:53:03 +0200 Helmut Grohne <helmut at subdivi.de>
> wrote:
> > Source: tevent
> > Version: 0.10.2-1
> > Tags: patch upstream
> > User: debian-cross at lists.debian.org
> > Usertags: ftcbfs
> > 
> > Thank you for applying my previous cross build patches. My previous
> > installment ended with:
> > 
> > > 5. waf has a mandatory run test for determining whether mkstemp
> > > works.
> > > 6. probably more
> > 
> > I've now looked into this and think that there are two bigger steps
> > to
> > solve these. In the "probably more" department, there is a
> > recurring
> > scheme of using a "CHECK_VALUEOF". It is used to determine the
> > value of
> > an integer. If that value happens to be a compile time constant, it
> > can
> > be determined using bisection. waf already does something similar
> > in
> > CHECK_SIZEOF. I've implemented it for CHECK_VALUEOF and it now
> > works
> > similar to autoconf's AC_COMPUTE_INT. In particular, it only does
> > the
> > expensive bisection during cross compilation. In a native build, it
> > continues to use the quick run test it did before. I've attached a
> > patch
> > for this.
> 
> Umm. waf in samba is doing many "bad" things which can be done in a
> more
> efficient way not requiring to run compiled binaries. Yes,
> sizeof(foo) is
> a good example, valueof is another example.
> 
> I think it is too much work to patch all these things out in debian.
> It might be a good idea to try to ping upstream about this, maybe
> they'll
> include similar change(s) to make cross-compilations easier.  But
> probably
> not in Debian.

Samba regularly accepts changes to improve cross-compilation.  We test
a lame cross-compilation mode in our autobuild and would love to have
both an improved test (that is more realistic) and any improvements our
user community can find. 

> I'd not spend more time on trying to make waf-based samba builds to
> be
> cross-compilable, unless upstream is actually willing to accept the
> work somehow. So far, it seems like upstream isn't willing even to
> accept simple spelling fixes.

We regularly accept patches that are correctly signed off and submitted
to GitLab per https://wiki.samba.org/index.php/Contribute

> FWIW, Helmut, what do you think about using qemu-user[-static] to
> help
> cross-compiling stuff? It should significantly help in situations
> like
> this one, to be able to run the small test binaries in an emulated
> mode,
> provided you do have the foreign libs installed on the system.  Yes
> it
> is not the fastest, but for sizeof/valueof tests like this it will
> Just Work, hopefully...

This would seem to be the best route forward, per:

https://wiki.samba.org/index.php/Waf#Using_--cross-execute

Andrew Bartlett

-- 
Andrew Bartlett (he/him)       https://samba.org/~abartlet/
Samba Team Member (since 2001) https://samba.org
Samba Team Lead, Catalyst IT   https://catalyst.net.nz/services/samba

Samba Development and Support, Catalyst IT - Expert Open Source
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