Quoting Vagrant Cascadian (2021-06-05 19:39:56)
> On 2021-06-05, Johannes Schauer Marin Rodrigues wrote:
> > Quoting Vagrant Cascadian (2021-06-05 03:09:52)
> >> When mmdebstrap produces a tarball directly, it sets different tarball
> >> options:
> >>
> >> # tar2sqfs and genext2fs do not support extended attributes
> >> if ($format eq "squashfs") {
> >> warning("tar2sqfs does not support extended attributes"
> >> . " from the 'system' namespace");
> >> push @taropts, '--xattrs', '--xattrs-exclude=system.*';
> >>
> >> But if you're trying to generate a squashfs image with different default
> >> compression (e.g. zstd), you have to pipe the mmdebstrap output to
> >> tar2sqfs. But in this case, tar is not passed the above options, as it
> >> is generating a tarball...
> >
> > yes. But you can filter the tarball and remove the system.* xattr later:
> >
> > mmdebstrap ... | mmtarfilter --pax-exclude=SCHILY.xattr.system.* | tar2sqfs
> > ...
>
> This might be worth mentioning in the mmdebstrap manpage! And updating
> the mmtarfilter manpage with --pax-exclude too... :)In fact, that functionality only exists in git so far, sorry. I'm waiting for the freeze to end so that I can upload a new mmdebstrap version to unstable. > >> Maybe I'm missing something, but it would be very nice to be able to at > >> least append to options passed to tar2sqfs (presuming it doesn't error > >> when passing two different --compressor arguments), rather than having to > >> extract them from the manpage and/or code, especially given that the tar > >> output changes when you create a regular tarball vs. when mmdebstrap is > >> aware that the eventual destination is a squashfs... > > > > Is that such a common task? Are you running mmdebstrap manually and find > > yourself piping it to tar2sqfs by hand? Do you maybe suggest that the > > default > > options might need changing? I'm trying to understand your use-case here. > > Well, *mostly* just to build zstd squashfs instead of xz (the > performance on various hardware I use is considerable better with zstd > defaults). Being able to set the compression type directly from > mmdebstrap would be nice! > > I think I also needed to pipe to tar2sqfs manually in the past to > workaround bugs that I think have since been fixed (e.g. the > --xattrs-exclude patches). But are you running mmdebstrap by hand or are you using it as part of a script? > The current default for tar2sqfs is xz, so passing --compressor xz is > redundant. Maybe I should just drop the "--compressor xz" option and use the tar2sqfs default and then you can post a bugreport about a good default with the tar2sqfs people instead of here. ;) > >> I'm also realizing that the squashfs call doesn't pass --num-jobs=0 to > >> tar2sqfs (similar to when creating a .tar.zst). > > > > Indeed that can be fixed. > > Apparently, the default for tar2sqfs is number of cores: > > --num-jobs, -j <count> > If libsquashfs was compiled with a thread pool based, > parallel data compressor, this option can be used to set > the number of compressor threads. If not set, the default > is the number of available CPU cores. > > So I guess that's not needed at all. Aha, cool. Thanks! cheers, josch
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