On Fri, Jan 17, 2014 at 04:34:29PM +0800, WANG Chao wrote:
[..]
> There is a problem with kdump saving the seed. And that is kdump
is
> started at the beginning of boot and you are assuming that by then
> systemd has restored the entropy pool from previously saved random seed.
I looked into the systemd services dependencies[1], I found that kdump
would always run after systemd-random-seed. That said, when kdump is
starting, /dev/urandom is already feed. And actually systemd-random-seed
service is started very early, same level with systemd-udevd,
systemd-journald etc. and systemd-random-seed is only depending on the /
mount.
[1]: I got this data by running `systemctl list-dependencies kdump`
I was trying to avoid making assumptions on the system service start
order. It works this way today what if order changes tomorrow. This
assumption is kind of subtle that kdump depends on /dev/urandom being
fed by the time service starts.
So I prefer that you first look for random-seed file so that we don't
assume service order dependencies. But if you don't like this, it is
ok. I am not too particular about it and can live with saving
/dev/urandom.
Thanks
Vivek