[systemd-devel] Plans to fix or provide alternative for lz4?

Lennart Poettering lennart at poettering.net
Sun Mar 1 03:04:20 PST 2015

On Thu, 26.02.15 05:55, Zbigniew Jędrzejewski-Szmek (zbyszek at in.waw.pl) wrote:

> On Thu, Feb 26, 2015 at 04:41:48AM +0000, Laszlo Papp wrote:
> > Hi,
> > 
> > it seems that the lz4 headers are broken when getting coredumps
> > generated. They cannot even be extracted by the lz4 tool itself, let
> > alone using them via the coredump controller util.
> > 
> > My system, which is Archlinux, is using lz4 127 and systemd 219.
> > 
> > My current workaround was to disable compression altogether for
> > coredumps in the corresponding config file, but it is suboptimal,
> > especially on embedded systems.
> The headers are different because when lz4 support was added, lz4 did
> not provide a library to write the headers so I added custom headers.
> You should be able to use coredumpctl to unpack the file.
> "Proper" lz4 support has been written, but lz4 upstream has trouble
> with keeping .so compatibility: https://code.google.com/p/lz4/issues/detail?id=147.
> So the question is whether to replace lz4 with something more stable
> or to ignore the issue and hope it doesn't happen again.

Maybe gzip might be a good compromise? Due to the importd logic we now
check for libz anyway in configure.ac, we might as well use it for the
journal. To my knowledge gzip is still a good compromise between
compression ratio on one hand and memory use/time on the other...


Lennart Poettering, Red Hat

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