Last time I saw it, I had just upgraded my CentOS 7 box with the 3.10.0-514
kernel and it rebooted already configured into debug mode. Not sure if this is a
?feature? of the newer kernels or not but glad to see that i?m not the only one
who had noticed this.
# awk -F\' '$1=="menuentry " {print i++ " : "
$2}' /etc/grub2.cfg
0 : CentOS Linux (3.10.0-514.6.2.el7.x86_64) 7 (Core)
1 : CentOS Linux (3.10.0-514.6.2.el7.x86_64) 7 (Core) with debugging
2 : CentOS Linux (0-rescue-7b37bcbe36eb420fb6426976c41b0aaf) 7 (Core)
3 : CentOS Linux (0-rescue-7b37bcbe36eb420fb6426976c41b0aaf) 7 (Core) with
debugging
On Feb 27, 2017, 8:40 PM -0500, Chris Adams <linux at cmadams.net>,
wrote:> Once upon a time, Thomas Eriksson <thomas.eriksson at
slac.stanford.edu> said:
> > I noticed that some, but not all, of my CentOS 7 machines have these
> > kernel parameters for turning on systemd debug level logging added to
> > the grub.cfg file.
>
> Yep, for each of the installed kernels, I have two GRUB entries: one
> with and one without debugging. It seems that when I install a new
> kernel, the debugging entry gets the "default" choice.
>
> I don't know what's adding them though.
> --
> Chris Adams <linux at cmadams.net
> _______________________________________________
> CentOS mailing list
> CentOS at centos.org
> https://lists.centos.org/mailman/listinfo/centos
On Tue, February 28, 2017 9:22 am, Rob DeSanno wrote:> Last time I saw it, I had just upgraded my CentOS 7 box with the > 3.10.0-514 kernel and it rebooted already configured into debug mode. Not > sure if this is a ???feature??? of the newer kernels or not but glad to > see that i???m not the only one who had noticed this. > > # awk -F\' '$1=="menuentry " {print i++ " : " $2}' /etc/grub2.cfg > 0 : CentOS Linux (3.10.0-514.6.2.el7.x86_64) 7 (Core) > 1 : CentOS Linux (3.10.0-514.6.2.el7.x86_64) 7 (Core) with debugging > 2 : CentOS Linux (0-rescue-7b37bcbe36eb420fb6426976c41b0aaf) 7 (Core) > 3 : CentOS Linux (0-rescue-7b37bcbe36eb420fb6426976c41b0aaf) 7 (Core) with > debuggingI am not certain if there is real harm to have kernel with all debug stuff running on production machines. Probably no harm security wise, the only unpleasant stuff is: you really would prefer to run as slim kernel as possible on production systems. If I'm wrong about "no harm", somebody chime in, I then will be really eager to address it on my boxes. Valeri> > On Feb 27, 2017, 8:40 PM -0500, Chris Adams <linux at cmadams.net>, wrote: >> Once upon a time, Thomas Eriksson <thomas.eriksson at slac.stanford.edu> >> said: >> > I noticed that some, but not all, of my CentOS 7 machines have these >> > kernel parameters for turning on systemd debug level logging added to >> > the grub.cfg file. >> >> Yep, for each of the installed kernels, I have two GRUB entries: one >> with and one without debugging. It seems that when I install a new >> kernel, the debugging entry gets the "default" choice. >> >> I don't know what's adding them though. >> -- >> Chris Adams <linux at cmadams.net >> _______________________________________________ >> CentOS mailing list >> CentOS at centos.org >> https://lists.centos.org/mailman/listinfo/centos > _______________________________________________ > CentOS mailing list > CentOS at centos.org > https://lists.centos.org/mailman/listinfo/centos >++++++++++++++++++++++++++++++++++++++++ Valeri Galtsev Sr System Administrator Department of Astronomy and Astrophysics Kavli Institute for Cosmological Physics University of Chicago Phone: 773-702-4247 ++++++++++++++++++++++++++++++++++++++++
The reason why I noticed was that telegraf was reporting context related issues even with selinux disabled. That?s when I noticed all of the debugging lines in dmesg as well as debug mode enabled in /proc/cmdline. On Feb 28, 2017, 10:49 AM -0500, Valeri Galtsev <galtsev at kicp.uchicago.edu>, wrote:> > On Tue, February 28, 2017 9:22 am, Rob DeSanno wrote: > > Last time I saw it, I had just upgraded my CentOS 7 box with the > > 3.10.0-514 kernel and it rebooted already configured into debug mode. Not > > sure if this is a ???feature??? of the newer kernels or not but glad to > > see that i???m not the only one who had noticed this. > > > > # awk -F\' '$1=="menuentry " {print i++ " : " $2}' /etc/grub2.cfg > > 0 : CentOS Linux (3.10.0-514.6.2.el7.x86_64) 7 (Core) > > 1 : CentOS Linux (3.10.0-514.6.2.el7.x86_64) 7 (Core) with debugging > > 2 : CentOS Linux (0-rescue-7b37bcbe36eb420fb6426976c41b0aaf) 7 (Core) > > 3 : CentOS Linux (0-rescue-7b37bcbe36eb420fb6426976c41b0aaf) 7 (Core) with > > debugging > > I am not certain if there is real harm to have kernel with all debug stuff > running on production machines. Probably no harm security wise, the only > unpleasant stuff is: you really would prefer to run as slim kernel as > possible on production systems. If I'm wrong about "no harm", somebody > chime in, I then will be really eager to address it on my boxes. > > Valeri > > > > > On Feb 27, 2017, 8:40 PM -0500, Chris Adams <linux at cmadams.net>, wrote: > > > Once upon a time, Thomas Eriksson <thomas.eriksson at slac.stanford.edu > > > said: > > > > I noticed that some, but not all, of my CentOS 7 machines have these > > > > kernel parameters for turning on systemd debug level logging added to > > > > the grub.cfg file. > > > > > > Yep, for each of the installed kernels, I have two GRUB entries: one > > > with and one without debugging. It seems that when I install a new > > > kernel, the debugging entry gets the "default" choice. > > > > > > I don't know what's adding them though. > > > -- > > > Chris Adams <linux at cmadams.net > > > _______________________________________________ > > > CentOS mailing list > > > CentOS at centos.org > > > https://lists.centos.org/mailman/listinfo/centos > > _______________________________________________ > > CentOS mailing list > > CentOS at centos.org > > https://lists.centos.org/mailman/listinfo/centos > > > > > ++++++++++++++++++++++++++++++++++++++++ > Valeri Galtsev > Sr System Administrator > Department of Astronomy and Astrophysics > Kavli Institute for Cosmological Physics > University of Chicago > Phone: 773-702-4247 > ++++++++++++++++++++++++++++++++++++++++ > _______________________________________________ > CentOS mailing list > CentOS at centos.org > https://lists.centos.org/mailman/listinfo/centos
On Tue, Feb 28, 2017 at 10:49 AM, Valeri Galtsev <galtsev at kicp.uchicago.edu> wrote:> > On Tue, February 28, 2017 9:22 am, Rob DeSanno wrote: > > Last time I saw it, I had just upgraded my CentOS 7 box with the > > 3.10.0-514 kernel and it rebooted already configured into debug mode. > Not > > sure if this is a ???feature?? of the newer kernels or not but glad to > > see that i???m not the only one who had noticed this. > > > > # awk -F\' '$1=="menuentry " {print i++ " : " $2}' /etc/grub2.cfg > > 0 : CentOS Linux (3.10.0-514.6.2.el7.x86_64) 7 (Core) > > 1 : CentOS Linux (3.10.0-514.6.2.el7.x86_64) 7 (Core) with debugging > > 2 : CentOS Linux (0-rescue-7b37bcbe36eb420fb6426976c41b0aaf) 7 (Core) > > 3 : CentOS Linux (0-rescue-7b37bcbe36eb420fb6426976c41b0aaf) 7 (Core) > with > > debugging > > I am not certain if there is real harm to have kernel with all debug stuff > running on production machines. Probably no harm security wise, the only > unpleasant stuff is: you really would prefer to run as slim kernel as > possible on production systems. If I'm wrong about "no harm", somebody > chime in, I then will be really eager to address it on my boxes. > > Valeri > >Main issue I've seen is that logs grow by an order of magnitude larger than when it's off, due to systemd being systemd and now running in debug mode. Other than disk space, it would affect any central logging system you have with lots of unnecessary traffic, and would also add a lot of IO, amplified if you have many machines running on a VM host. ~ Brian Mathis @orev