On Thu, 12.09.13 07:53, Daniel J Walsh (dwalsh(a)redhat.com) wrote:
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Basically looking at compressing the policy file to shrink SELinux footprint
in the minimal install/cloud image.
Currently the policy modules (pp files) are shipped with bzip compression but
the actually policy file.
But the /etc/selinux/targeted/policy/policy.29 is not compressed. systemd and
load_policy use libselinux to read in the policy file and load it into the
kernel, so since systemd currently uses libxz, I figured this would be the
best solution to add libxz support to libselinux.
ls -l /etc/selinux/targeted/policy/policy.29*
- -rw-r--r--. 1 root root 2703245 Sep 11 13:56
- -rw-r--r--. 1 root root 395072 Sep 11 13:56
Worth the effort?
Well, you might buy smaller footprint with slower boot time, but I
figure without trying it there's no way to know that for sure.
(That said, our minimal image is a couple of 100mb still, iirc, so 2mb
is not thaaaat much.)
Should I use a different algorithm?
Advise on using libxz? Keep memory small?
I think nowadays it's either gzip or xz, and everything else is not
interesting, as the others either are slower or compress worses, and
most importantly: libgz/liblzma are deps of the core OS anyway and
included in the minimal image anyway and are also already mapped into
memory, so come basically free.
Lennart Poettering - Red Hat, Inc.