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Re: [debian-devel] Hidden timeskew problems might show up on 2.6.x kernels



On Tue, Jan 13, 2004 at 09:59:10PM +0000, Magos?nyi ?rp?d wrote:
> A levelez?m azt hiszi, hogy Jeroen van Wolffelaar a k?vetkez?eket ?rta:
> 
> > It turned out, that 2.6.x kernels support mtimes of high precision
> > (nanoseconds rather than just seconds). Since in the diff file, the
> > Makefile.in was patched before the Makefile.am, the .am got a newer
> > mtime, and caused automake to be invoked. Swapping them around in the
> 
> I cannot see your point after this. Some observations:
> -If the build have fucked up because an automake run, then
> 	there should be some problems unrelated to clock
> 	precision.

The problem was that my sponsor had another version of automake than
upstream. In my chroot, I didn't have any automake at all.

I deliberately did not rerun automake, because
1) this might introduce new problems
2) is unreproducable to other people unless they know which
automake/autoconf etc I used

If I were to install the same automake & autoconf as upstream, I assume
it would have went okay (didn't test though, because I have no reason
to)

> -You are in trouble if the outcome of the build depends on the
> 	relative mtime of any combination of source files.

Because of my previous point, I did manually patch *both* Makefile.am
and Makefile.in, consistently with eachother (it was a simple literal
string replace, so it was easy to manually induce how .in would be
changed based on my .am changes. I could also have run automake again,
with the correct version, and I suppose that would have been okay too.
Again, the correct automake version is not recorded in build-depends, so
will need to be manually checked if you choose to regenerate the
Makefile.in

> -Makefile.in was not a source file in your case. It should have
> 	been deleted by debian/rules clean.

It was, both Makefile.in and Makefile.am were in upstream. See further above.


And, it remains true that without dpkg-source passing the -Z flag to
patch, build success could depend on your kernel due to timestamp
problems, and that the order in the .diff does matter in regard to
whether some (unspecified!) version of automake will be invoked on
build.

--Jeroen

-- 
Jeroen van Wolffelaar
+31-30-253 4499
Jeroen@A-Eskwadraat.nl
http://Jeroen.A-Eskwadraat.nl



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