Messages in this thread | | | Date | Thu, 12 Nov 2020 08:59:18 +0900 | From | Sergey Senozhatsky <> | Subject | Re: [PATCH 2/2] printk/console: Allow to disable console output by using console="" or console=null |
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On (20/11/11 14:54), Petr Mladek wrote: > The commit 48021f98130880dd74 ("printk: handle blank console arguments > passed in.") prevented crash caused by empty console= parameter value. > > Unfortunately, this value is widely used on Chromebooks to disable > the console output. The above commit caused performance regression > because the messages were pushed on slow console even though nobody > was watching it. > > Use ttynull driver explicitly for console="" and console=null > parameters. It has been created for exactly this purpose. > > It causes that preferred_console is set. As a result, ttySX and ttyX > are not used as a fallback. And only ttynull console gets registered by > default. > > It still allows to register other consoles either by additional console= > parameters or SPCR. It prevents regression because it worked this way even > before. Also it is a sane semantic. Preventing output on all consoles > should be done another way, for example, by introducing mute_console > parameter. > > Link: https://lore.kernel.org/r/20201006025935.GA597@jagdpanzerIV.localdomain > Suggested-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com> > Signed-off-by: Petr Mladek <pmladek@suse.com>
Acked-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
-ss
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