Re: pre-change: lower printk setting after switching to real root
On Do, 21.07.22 05:56, Colin Walters (walt...@verbum.org) wrote: > >> We recently did > >> https://github.com/coreos/fedora-coreos-config/pull/1840 for Fedora > >> CoreOS (more background: > >> https://github.com/coreos/fedora-coreos-tracker/issues/1244 ) and > >> I'd like to consider applying this to all Fedora editions. > >> > >> There'd be no impact on desktop systems (commonly installed via > >> Anaconda and hence using `quiet`). > >> > >> The benefit is for server systems where we *do* want some kernel > >> output at boot, but once we've successfully booted we don't want to > >> emit a message every time podman/docker creates a bridge device for > >> example. > >> > >> Concretely today, I noticed that the RHEL 8.6 Cloud Guest image also > >> does not include `quiet` and so the kernel console log is full of > >> the same spam at runtime, and I think it makes sense to do this > >> change across all Fedora derivatives. > > > > I am note entirely sure if this feature has merit or not, > > Definitely interested in your opinion, because...a bikeshed here is > where to put this unit if it's not systemd. The thing is that serial console output from the kernel is really slow and slows down the kernel (because it's synchronous, in some way). And this slowness is not just minor issue you can ignore, it's actually massive, if you do that across your fleet. OTOH I am also not sure that this kinda of cosmetics really matter on servers. They are usually not interacted with on their console, except for debugging. But in that case, wouldn't it be better to just allow the whole logs to go through? So there are reasons not to log to the console needlessly, and there are reasons to always log to the console to improve debugging. Hence, it doesn't appear to me that it is clear that doing what you are proposing is universially a good idea. It kinda feels as if in 30% of uses it might be beneficial, in 30% people would hate it, and in 30% people might not care... That's why I don't really want to agree or disagree with the proposal, it's not clear at all to me that what you are doing there is a good idea across the board. It might be in the coreos case, if you say so, but universally, i am not sure. Lennart -- Lennart Poettering, Berlin ___ devel mailing list -- devel@lists.fedoraproject.org To unsubscribe send an email to devel-le...@lists.fedoraproject.org Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org Do not reply to spam on the list, report it: https://pagure.io/fedora-infrastructure
Re: pre-change: lower printk setting after switching to real root
On Tue, Jul 19, 2022, at 12:24 PM, Lennart Poettering wrote: > On Fr, 15.07.22 10:03, Colin Walters (walt...@verbum.org) wrote: > >> We recently did >> https://github.com/coreos/fedora-coreos-config/pull/1840 for Fedora >> CoreOS (more background: >> https://github.com/coreos/fedora-coreos-tracker/issues/1244 ) and >> I'd like to consider applying this to all Fedora editions. >> >> There'd be no impact on desktop systems (commonly installed via >> Anaconda and hence using `quiet`). >> >> The benefit is for server systems where we *do* want some kernel >> output at boot, but once we've successfully booted we don't want to >> emit a message every time podman/docker creates a bridge device for >> example. >> >> Concretely today, I noticed that the RHEL 8.6 Cloud Guest image also >> does not include `quiet` and so the kernel console log is full of >> the same spam at runtime, and I think it makes sense to do this >> change across all Fedora derivatives. > > I am note entirely sure if this feature has merit or not, Definitely interested in your opinion, because...a bikeshed here is where to put this unit if it's not systemd. For CoreOS, we have this nice "overlay" git repository for stuff like this that isn't an RPM, it has a lot of our miscellaneous systemd units and config files and such; so we can just do a pull request, have that pull request go through CI and merge and then it gets baked into the image and ship...no "manual package builds". The closest analogue in the yum world (i.e. only understands RPMs) is probably the generic-release type packages. So in theory it could go there. But this all said...it perhaps is worth considering the alternative, which is just this one-liner diff to the kernel config (AFAIK): diff --git a/kernel-x86_64-fedora.config b/kernel-x86_64-fedora.config index 517763fc9..b4b5708a3 100644 --- a/kernel-x86_64-fedora.config +++ b/kernel-x86_64-fedora.config @@ -981,7 +981,7 @@ CONFIG_COMPAT_32BIT_TIME=y # CONFIG_COMPILE_TEST is not set CONFIG_CONFIGFS_FS=y CONFIG_CONNECTOR=y -CONFIG_CONSOLE_LOGLEVEL_DEFAULT=7 +CONFIG_CONSOLE_LOGLEVEL_DEFAULT=4 CONFIG_CONSOLE_LOGLEVEL_QUIET=3 CONFIG_CONTEXT_SWITCH_TRACER=y # CONFIG_CONTEXT_TRACKING_FORCE is not set The implications to that are obviously much larger, which is why I hesitated to propose it. While the stream of debug-level spew for servers has caused serious problems, it feels odd to me to switch servers to be entirely quiet by default. I am *certain* there are people who are doing CI/testing systems and are gathering the kernel console today and expect non-quiet output by default. But, this is also a much simpler change to understand, and anyone who wants it can start specifying e.g. `debug` on the kernel command line. I'm certainly curious about the opinions of the kernel maintainers in particular here. ___ devel mailing list -- devel@lists.fedoraproject.org To unsubscribe send an email to devel-le...@lists.fedoraproject.org Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org Do not reply to spam on the list, report it: https://pagure.io/fedora-infrastructure
Re: pre-change: lower printk setting after switching to real root
On Tue, Jul 19, 2022, at 12:24 PM, Lennart Poettering wrote:
>
> by something like this:
>
>
> ExecStart=/usr/bin/systemd-tmpfiles --create -
> StandardInputText=f /run/sysctl.d/01-coreos-printk.conf - - - - kernel.printk
> 4
>
>
> Benefits: no shell, single process forked, no explicit selinux stuff,
> or explicit mkdir, and other MACs will be honoured too if they exist.
Unfortunately doesn't work today since:
[ 243.300955] audit: type=1400 audit(1658251774.506:317): avc: denied {
getattr } for pid=1801 comm="systemd-sysctl"
path="/run/sysctl.d/01-coreos-printk.conf" dev="tmpfs" ino=934
scontext=system_u:system_r:systemd_sysctl_t:s0
tcontext=system_u:object_r:var_run_t:s0 tclass=file permissive=1
But yes, I will look at getting that added to policy.
(FTR there was also a missing `=` in the sysctl text)
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Re: pre-change: lower printk setting after switching to real root
On Fr, 15.07.22 10:03, Colin Walters (walt...@verbum.org) wrote: > We recently did > https://github.com/coreos/fedora-coreos-config/pull/1840 for Fedora > CoreOS (more background: > https://github.com/coreos/fedora-coreos-tracker/issues/1244 ) and > I'd like to consider applying this to all Fedora editions. > > There'd be no impact on desktop systems (commonly installed via > Anaconda and hence using `quiet`). > > The benefit is for server systems where we *do* want some kernel > output at boot, but once we've successfully booted we don't want to > emit a message every time podman/docker creates a bridge device for > example. > > Concretely today, I noticed that the RHEL 8.6 Cloud Guest image also > does not include `quiet` and so the kernel console log is full of > the same spam at runtime, and I think it makes sense to do this > change across all Fedora derivatives. I am note entirely sure if this feature has merit or not, but I don't want to comment on that. However, I'd like to suggest that if you do this, please consider replacing this line: ExecStart=/bin/bash -euo pipefail -c 'mkdir -p /run/sysctl.d && chcon --reference=/etc/sysctl.d /run/sysctl.d && echo "kernel.printk = 4" > /run/sysctl.d/01-coreos-printk.conf' by something like this: ExecStart=/usr/bin/systemd-tmpfiles --create - StandardInputText=f /run/sysctl.d/01-coreos-printk.conf - - - - kernel.printk 4 Benefits: no shell, single process forked, no explicit selinux stuff, or explicit mkdir, and other MACs will be honoured too if they exist. Lennart -- Lennart Poettering, Berlin ___ devel mailing list -- devel@lists.fedoraproject.org To unsubscribe send an email to devel-le...@lists.fedoraproject.org Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org Do not reply to spam on the list, report it: https://pagure.io/fedora-infrastructure
Re: pre-change: lower printk setting after switching to real root
On Fri, Jul 15, 2022 at 10:03:48AM -0400, Colin Walters wrote: > We recently did https://github.com/coreos/fedora-coreos-config/pull/1840 for > Fedora CoreOS (more background: > https://github.com/coreos/fedora-coreos-tracker/issues/1244 ) and I'd like to > consider applying this to all Fedora editions. > > There'd be no impact on desktop systems (commonly installed via Anaconda and > hence using `quiet`). > > The benefit is for server systems where we *do* want some kernel output at > boot, but once we've successfully booted we don't want to emit a message > every time podman/docker creates a bridge device for example. > > Concretely today, I noticed that the RHEL 8.6 Cloud Guest image also does not > include `quiet` and so the kernel console log is full of the same spam at > runtime, and I think it makes sense to do this change across all Fedora > derivatives. It sounds like a reasonable idea. I assume someone could override it when/if they needed/wanted the more verbose messages? I'd say write up a change on it. kevin signature.asc Description: PGP signature ___ devel mailing list -- devel@lists.fedoraproject.org To unsubscribe send an email to devel-le...@lists.fedoraproject.org Fedora Code of Conduct: https://docs.fedoraproject.org/en-US/project/code-of-conduct/ List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/devel@lists.fedoraproject.org Do not reply to spam on the list, report it: https://pagure.io/fedora-infrastructure
