linux-kernel - Re: [PATCH] efistub: Lower default log level

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Message-ID: <CAMj1kXG=zG8j+cr0gNMpkKRvdekqMR-EiEkMHiFgRvbaWy9aKg@mail.gmail.com>
Date: Sun, 24 Aug 2025 10:31:35 +1000
From: Ard Biesheuvel <ardb@...nel.org>
To: Jan Kiszka <jan.kiszka@...mens.com>
Cc: Aaron Kling <webgeek1234@...il.com>, linux-efi@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] efistub: Lower default log level

On Sat, 16 Aug 2025 at 16:52, Jan Kiszka <jan.kiszka@...mens.com> wrote:
>
> On 15.07.25 03:35, Ard Biesheuvel wrote:
> > On Tue, 8 Jul 2025 at 17:31, Aaron Kling <webgeek1234@...il.com> wrote:
> >>
> >> On Tue, Jul 8, 2025 at 2:30 AM Aaron Kling via B4 Relay
> >> <devnull+webgeek1234.gmail.com@...nel.org> wrote:
> >>>
> >>> From: Aaron Kling <webgeek1234@...il.com>
> >>>
> >>> Some uefi implementations will write the efistub logs to the display
> >>> over a splash image. This is not desirable for debug and info logs, so
> >>> lower the default efi log level to exclude them.
> >>>
> >>> Suggested-by: Ard Biesheuvel <ardb@...nel.org>
> >>> Signed-off-by: Aaron Kling <webgeek1234@...il.com>
> >>> ---
> >>>  drivers/firmware/efi/libstub/printk.c | 4 ++--
> >>>  1 file changed, 2 insertions(+), 2 deletions(-)
> >>>
> >>> diff --git a/drivers/firmware/efi/libstub/printk.c b/drivers/firmware/efi/libstub/printk.c
> >>> index 3a67a2cea7bdf1aa215d48dbf9ece4ceec6e4c28..bc599212c05dd746a9c54abbbe61a4bf70f1a8c4 100644
> >>> --- a/drivers/firmware/efi/libstub/printk.c
> >>> +++ b/drivers/firmware/efi/libstub/printk.c
> >>> @@ -5,13 +5,13 @@
> >>>  #include <linux/ctype.h>
> >>>  #include <linux/efi.h>
> >>>  #include <linux/kernel.h>
> >>> -#include <linux/printk.h> /* For CONSOLE_LOGLEVEL_* */
> >>> +#include <linux/kern_levels.h>
> >>>  #include <asm/efi.h>
> >>>  #include <asm/setup.h>
> >>>
> >>>  #include "efistub.h"
> >>>
> >>> -int efi_loglevel = CONSOLE_LOGLEVEL_DEFAULT;
> >>> +int efi_loglevel = LOGLEVEL_NOTICE;
> >>>
> >>>  /**
> >>>   * efi_char16_puts() - Write a UCS-2 encoded string to the console
> >>>
> >>> ---
> >>> base-commit: d7b8f8e20813f0179d8ef519541a3527e7661d3a
> >>> change-id: 20250708-efi-default-loglevel-4da5a36cac87
> >>>
> >>> Best regards,
> >>> --
> >>> Aaron Kling <webgeek1234@...il.com>
> >>
> >> This patch was originally suggested a few months ago [0], but as far
> >> as I can tell was never queued for merge. Since I'm also hitting a
> >> case where this is relevant, I'm sending this in to bring attention
> >> back to it.
> >>
> >
> > I've queued this up now - thanks.
> >
>
> And how can I get back the loglevel info? It seems I can only choose
> between notice, silent and debug now. And the latter two only by also
> touching the kernel's loglevel.
>
> I'm particularly missing [1] in my UART logs now which is helpful in
> understanding this essential system state.
>

Hi Jan,

Is efi=debug too noisy for you?