Re: [PATCH] maint: tweak xz options to compress the release tarball even more

[Jim Meyering]

On Wed, Jan 11, 2017 at 6:31 PM, Antonio Diaz Diaz <address@hidden> wrote:
> Jim Meyering wrote:
>>
>> -export XZ_OPT = -8e
>> +export XZ_OPT = --lzma2=preset=9e,dict=48MiB,pb=0
>
>
> Isn't this going to impact the use of pristine-tar?
> https://packages.debian.org/sid/pristine-tar
>
> https://github.com/pah/pristine-tar/blob/master/pristine-xz states that:
> --------------------------------------------------------------------
> The approach used to regenerate the original xz file is to figure out
> how it was produced -- what compression level was used, etc. Currently
> support is poor for xz files produced with unusual compression options.
> --------------------------------------------------------------------

I would not let the existence of limitations in such a tool block the
use of options to get better compression.

But if it is an issue, then we can see it as an opportunity for
improvement of pristine-tar. The dictionary size is already readily
available via `xz -vv --list ...`, and if there is not yet a way to
directly derive that `pb=0` setting, I'll bet its use can be derived
without too much effort.