[PATCH] build: SDK/IB reproducible and faster compression

[Paul Spooren]

On 21.08.20 06:47, Matthias Schiffer wrote:
> Did you have a look at the zstd patches I sent a while ago? zstd is
> superior to xz in most cases - the only reason I didn't merge the patches
> yet was that all of our phase2 buildbots would need to have zstd installed
> to extract the new SDK before we can actually switch (and I'm not sure who
> can take care of that - jow?).

I'm aware of the patches and like the step forward to zstd! However I 
see the downstream concerns as well. How about applying my patches and 
you send a rebased version of your zstd patches, including the changes 
for reproducibility?

Our buildbot containers are based on debian:9. When installing the zstd 
package it works fine with tar (tar -I zstd -xf foobar.tar.zst). If 
desired I can update the containers to contain zstd.

buildbot at 00801fffe9e2:~$ tar --version
tar (GNU tar) 1.29

Starting with tar 1.31  we could also use `--zstd`, which is however not 
even part of Debian 10.

I have no access to the ansible.git repository, wouldn't it be enough to 
just do the following change?

-  sdk_pattern = openwrt-sdk-*.tar.xz
+ sdk_pattern = openwrt-sdk-*.tar.*

The following line in buildbot.git/phase2 could be duplicated and run 
based on which branch is used:
https://git.openwrt.org/?p=buildbot.git;a=blob;f=phase2/master.cfg;h=5ed7eff5728da299dee7e01ff416fc11533bf13a;hb=HEAD#l409

For an easier migration maybe I'd be nice to create both zstd and xz for 
a month (week?), that could be implemented in an updated version of you 
patchset.

> The mtime part of this patch makes sense.
Thanks