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Bug#976462: debian bug 976462

Hi Sean,

On Wed, 2021-03-17 at 09:36 -0700, Sean Whitton wrote:
> On Wed 10 Mar 2021 at 04:54PM +01, Mark Wielaard wrote:
> > For reference, this is the dwz bug for [dwz] Support compressed debug
> > sections: https://sourceware.org/bugzilla/show_bug.cgi?id=24725
> > 
> > It has low priority because it has a simple workaround:
> > you could use eu-elfcompress before/after the dwz run
> > 
> > $ eu-elfcompress --type=none ./a.out
> > $ dwz ./a.out
> > $ eu-elfcompress --type=zlib ./a.out
> Thanks for the input.  In any case in which the reason not to use
> compressed debug symbols is something to do with package builds, a
> workaround of this form could be used.

I don't know how Debian does package builds exactly (I am a Debian
user, but only have experience with packaging for Fedora). But IMHO it
would be nice if this (usage of dwz) was something standard and didn't
need workarounds.

> Then, the only tool compatibility reasons not to use compressed debug
> symbols are (i) tools that users who have the symbols installed want to
> run; and (ii) complicated debhelper order-of-operation issues which make
> it difficult to use the above workaround.
> Given that the debhelper maintainer said that he doesn't mind whether or
> not compression is turned on, I think we can eliminate (ii).
> Looking back through the thread, the closest thing we have to (i) is two
> bugs in Valgrind.  However, those bugs are both marked as resolved.

I think I fixed those upstream for valgrind 3.17.0, just released (I
also happen to work on upstream valgrind). But I am not really happy
with it. It feels like a hack to workaround something that is actually
broken. It is easy to workaround, but ugly IMHO.

> So, I conclude that we still haven't seen concrete tooling problems
> which would give us good reasons to disable compression.

One tool Debian isn't using yet, but which I hope you will consider
adopting is debugedit, which is fairly new because we just now lifted
it from rpm in the hope that it will be useful for non-rpm using
distros too: https://sourceware.org/debugedit/

It too doesn't handle compressed debug elf sections at the moment:

Not saying Debian should do debuginfo/debugsource packaging the same as
rpm based distros (instead of debugedit, Debian seems to use -fdebug-
prefix-map to create reproducible builds, which might or might not be
an interesting idea to adopt for other distros). But it would be nice
if we can share some of the tooling around it. Not having compressed
debug ELF sections makes that slightly easier.



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