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Bug#766708: Processed: Re: Bug#766708: breaks multiarch cross building

Hi Don,

Thanks for taking this up.

On Sun, Oct 26, 2014 at 02:59:13PM -0700, Don Armstrong wrote:
> Matthias: is the primary concern of including this patch one of
> maintenance burden, not primarily technical?

If you want Matthias to answer your question, I think that you may want
to Cc him, but since you know that very well, I am not doing so now.

> Could you provide some background for the CTTE on how much maintenance
> burden we're talking about, and what recent bugs have resulted from this
> particular patchset?

Since it is my interest to not cause more work on Matthias, I will try
to summarize his POV.

The most obvious bug is the one mentioned in the patch: #760770
It is about a bug in the implementation of with_deps_on_target_arch (the
contended feature).

Other bugs that may be relevant here are the ones that Matthias filed
against cross-gcc-4.9-* (packages that make use of
with_deps_on_target_arch). These are:
 arm64: #766614+#766617 (appear to be duplicates) #766624
 armel: #766616 #766625
 armhf: #766619 #766626
 mipsel: #766613 #766623
 powerpc: #766618 #766621
 ppc64el: #766615 #766622

The left bugs are titled "... is functional incomplete". The right bugs
are titled "the package fails to build from source on buildds and has
unmet dependencies". Discussion appears to take place on the armhf bugs.

Of the issues mentioned in those bugs the following appear to be not
specific to the cross-gcc-* packaging, but specific to the
with_deps_on_target_arch and DEB_CROSS_NO_BIARCH mechanisms:

1) The use of cross-architecture dependencies. Even though this is
   supported by dpkg and apt, it means that packages with cross
   architecture dependencies can only be installed after activating the
   relevant architecture with dpkg --add-architecture. The packages are
   thus uninstallable in a standard system. This limitation is the
   essence of with_deps_on_target_arch.
   (Right bugs)

2) The compilers are not functionally equivalent to the native
   compilers. This has two nuances. The cross-gcc-* packages do not
   build gobjc and golang even though the with_deps_on_target_arch
   mechanism supports this operation. But even disregarding this, the
   resulting cross compilers do something different from the native
   ones. Matthias has been asked[1] to elaborate on this difference and
   I think he is in a better position to make his case here.
   (Left bugs)

A third category of bugs that comes to my mind is the ones I filed or
was involved with: #742358 #742539 #743718 #743764 #744265 #744782
#745267 #747526 #751001 #751919 #758408 #743342
A significant portion of these was specific to either
with_deps_on_target_arch or DEB_CROSS_NO_BIARCH and I was not the only
one filing patches: #716795 #742606
All of these were processed by Matthias in a timely manner.

Matthias was involved in all of the bugs mentioned here and most of the
bugs are in direct connection to the with_deps_on_target_arch and
DEB_CROSS_NO_BIARCH mechanisms.  This is certainly not a negligible

Of course, this is not exhaustive, but it may save Matthias time digging
up bug numbers at least.

I sincerely hope that this message furthers the cause.


[1] https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=766619#10

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