Re: [Minios-devel] [UNIKRAFT PATCH] lib/ukdebug: print DLVL_EXTRA messages only in debug build

[Florian Schmidt <florian@xxxxxxxxx>]

Hi,

so after reading your's and Simon's answer, I'm still not quite clear 
about one thing. Is this planned to be per-subsystem or not? It sounded 
to me like it's not, and it's governed by a global define UK_DEBUG for 
all subsystems.
Or is it really strictly just for temporary debugging, i.e., a patch 
applied to staging/master should never have any uk_printd() calls in it?
Cheers,
Florian

On 08/01/2018 12:03 PM, Yuri Volchkov wrote:
> Hi,
>
> > I kinda like approaches like the linux kernel has, which allows you to
> > set debug output per subsystem level (which I guess in our case would
> > be libraries)
> In fact the proposal was to do it similar to linux kernel scheme. Here
> is a sentence from
> https://www.kernel.org/doc/html/v4.10/process/coding-style.html
>
>   "While the other pr_XXX() functions print unconditionally, pr_debug()
>    does not; it is compiled out by default, unless either DEBUG is
>    defined or CONFIG_DYNAMIC_DEBUG is set."
>
> Matching it to what Simon wrote:
> 1) uk_printk is equivalent to linux's printk with levels up to KERN_INFO
>
> 2) uk_printd is equivalent to linux's pr_debug(). However, in linux just
>     defining "DEBUG" for a file or subsystem is not enough, you also need
>     to change the printk level to KERN_DEBUG (e.g. echo 7 >
>     /proc/sys/kernel/printk). The same happens in current patch I have
>     sent, but the idea is to make debug output independent from the
>     current selected level in the future.
>
>
> > because global log levels of high verbosity can end up drowning you in
> > messages.
> Right, non-debug output should be readable even at maximum verbosity
> level. If a print spits to many messages it either should be pr_debug
> (or whatever we name it), or, it should be rate limited.
>
> > However, I'm aware that's a bit of a larger redesign, so I'm not sure we
> > want to go for it at the moment.
> This is dynamic print. We will get there eventually. This patch is a
> first baby step towards it.
>
> -Yuri.
>
> Florian Schmidt <florian@xxxxxxxxx> writes:
>
> > Hi everyone,
> >
> > On 07/31/2018 03:05 PM, Simon Kuenzer wrote:
> > > Give me a +1/0/-1.
> > I'm a 0 on this one.
> >
> > I agree that it's (slightly) less confusing than the current situation.
> > Then again, I kinda like approaches like the linux kernel has, which
> > allows you to set debug output per subsystem level (which I guess in our
> > case would be libraries) because global log levels of high verbosity can
> > end up drowning you in messages.
> >
> > However, I'm aware that's a bit of a larger redesign, so I'm not sure we
> > want to go for it at the moment.
> >
> > Cheers, Florian
> >
> > _______________________________________________
> > Minios-devel mailing list
> > Minios-devel@xxxxxxxxxxxxxxxxxxxx
> > https://lists.xenproject.org/mailman/listinfo/minios-devel
_______________________________________________
Minios-devel mailing list
Minios-devel@xxxxxxxxxxxxxxxxxxxx
https://lists.xenproject.org/mailman/listinfo/minios-devel