Messages in this thread | | | Date | Mon, 20 Jun 2022 19:03:30 +0200 | From | "Jason A. Donenfeld" <> | Subject | Re: [PATCH v3] printk: allow direct console printing to be enabled always |
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Hi Petr,
On Mon, Jun 20, 2022 at 06:58:13PM +0200, Petr Mladek wrote: > On Mon 2022-06-20 01:33:02, Jason A. Donenfeld wrote: > > In 5.19, there are some changes in printk message ordering / > > interleaving which leads to confusion. The most obvious (and benign) > > example appears on system boot, in which the "Run /init as init process" > > message gets intermixed with the messages that init actually writes() to > > stdout. For example, here's a snippet from build.wireguard.com: > > > > --- a/lib/Kconfig.debug > > +++ b/lib/Kconfig.debug > > @@ -35,6 +35,18 @@ config PRINTK_CALLER > > no option to enable/disable at the kernel command line parameter or > > sysfs interface. > > > > +config PRINTK_DIRECT > > + bool "Attempt to flush printk output immediately" > > + depends on PRINTK > > + help > > + Rather than using kthreads for printk output, always attempt to write > > + to the console immediately. This has performance implications, but > > + will result in a more faithful ordering and interleaving with other > > + processes writing to the console. > > + > > + Say N here unless you really need this. This may also be controlled > > + at boot time with printk.direct=0/1. > > + > > I am fine with the patch except for the config option. Is there > any particular reason why we need it, please?
It's a debug option that I'd like to be able to easily build my CI kernels with, just like various other debug options.
Jason
> We should be careful to add new build options in general because they > make building the kernel more complicated. People need to understand > what each option is about and what they want.
This one doesn't, really. It'd hidden away in the debug menu.
Jason
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