bug#21767: Matching debug symbol and package versions

bug#21767: Matching debug symbol and package versions

[Benno Evers]

Hi all,

assume I have installed some package

     /gnu/store/xxx-daemon-1.0

After a while I notice that it's inexplicably hanging, so I do 'guix 
package -i daemon-1.0:debug', attach to the daemon with gdb, and...no 
debug symbols can be loaded! Turns out, in the meantime the hash has 
changed so i installed

     /gnu/store/yyy-daemon-1.0:debug

It seems to me that there is currently no possibility to get the correct 
debug symbols. Worse, as civodul mentioned in chat, the package hash is 
part of the symbols itself, so I can't even cheat and force gdb manually 
to use the symbols for version yyy.

bug#21767: Matching debug symbol and package versions

[Ludovic Courtès]

Benno Evers <benno@bmevers.de> skribis:

> assume I have installed some package
>
>     /gnu/store/xxx-daemon-1.0
>
> After a while I notice that it's inexplicably hanging, so I do 'guix
> package -i daemon-1.0:debug', attach to the daemon with gdb, and...no
> debug symbols can be loaded! Turns out, in the meantime the hash has
> changed so i installed
>
>     /gnu/store/yyy-daemon-1.0:debug

One thing that could be done, maybe, is for ‘guix package -i’ to try to
infer the right item to install.

That is, when running “guix package -i foo:bar”:

  1. If no ‘foo’ is present in the profile, install the latest
     ‘foo:bar’, as is already the case.

  2. If another output of ‘foo’ is already installed, do:

     2a. Retrieve the .drv for that item using ‘query-path-info’.

         i. If the .drv is present, parse it, and use the outputs
            specified therein–i.e., the one that match.

         ii. If the .drv is missing, well, install the latest ‘foo:bar’.

The obvious problem is that this all sounds a bit complex, and it’s
unclear whether case (i) would sufficiently frequent to justify this
complexity.

Thoughts?

Thanks,
Ludo’.

bug#21767: Matching debug symbol and package versions

[Efraim Flashner]

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On Tue, 27 Oct 2015 16:56:23 +0100
ludo@gnu.org (Ludovic Courtès) wrote:

> Benno Evers <benno@bmevers.de> skribis:
> 
> > assume I have installed some package
> >
> >     /gnu/store/xxx-daemon-1.0
> >
> > After a while I notice that it's inexplicably hanging, so I do 'guix
> > package -i daemon-1.0:debug', attach to the daemon with gdb, and...no
> > debug symbols can be loaded! Turns out, in the meantime the hash has
> > changed so i installed
> >
> >     /gnu/store/yyy-daemon-1.0:debug  
> 
> One thing that could be done, maybe, is for ‘guix package -i’ to try to
> infer the right item to install.
> 
> That is, when running “guix package -i foo:bar”:
> 
>   1. If no ‘foo’ is present in the profile, install the latest
>      ‘foo:bar’, as is already the case.
> 
>   2. If another output of ‘foo’ is already installed, do:
> 
>      2a. Retrieve the .drv for that item using ‘query-path-info’.
> 
>          i. If the .drv is present, parse it, and use the outputs
>             specified therein–i.e., the one that match.
> 
>          ii. If the .drv is missing, well, install the latest ‘foo:bar’.
> 
> The obvious problem is that this all sounds a bit complex, and it’s
> unclear whether case (i) would sufficiently frequent to justify this
> complexity.
> 
> Thoughts?

Less complex would be `guix package -i foo:bar` to effectively be `guix
package -i foo foo:bar`. But then if you really only wanted foo:bar you'd
have to follow up with `guix package -r foo`.
-- 
Efraim Flashner   <efraim@flashner.co.il>   אפרים פלשנר
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bug#21767: Matching debug symbol and package versions

[Ludovic Courtès]

Efraim Flashner <efraim@flashner.co.il> skribis:

> Less complex would be `guix package -i foo:bar` to effectively be `guix
> package -i foo foo:bar`.

But I think that’s not necessarily what you’d expect, nor what you’d want.

Ludo’.

bug#21767: Matching debug symbol and package versions

[Ludovic Courtès]

Benno Evers <benno@bmevers.de> skribis:

> assume I have installed some package
>
>     /gnu/store/xxx-daemon-1.0
>
> After a while I notice that it's inexplicably hanging, so I do 'guix
> package -i daemon-1.0:debug', attach to the daemon with gdb, and...no
> debug symbols can be loaded! Turns out, in the meantime the hash has
> changed so i installed
>
>     /gnu/store/yyy-daemon-1.0:debug

I realized that I quickly focused on the issue without looking at the
more general context.

The “in the meantime” above means that you had run ‘guix pull’ or
similar, thereby making the previous package recipe unavailable and
leaving you unable to install matching debugging symbols.

On my laptop, I typically run ‘guix package -u’ every time I do ‘guix
pull’, so I cannot find myself in a situation where I’m unable to
install debugging symbols of already installed packages.

This is just to say that the scenario described here can indeed happen,
but is probably not that common.  And I don’t mean this to be an excuse
to avoid difficult work.  ;-)

I think that the solutions I proposed are worse than the problem,
because they’re complex and would depend on external state, thus making
them look non-deterministic.

So I think I’ll punt and mark it as “wontfix.”

Thoughts?

Ludo’.