[PATCH] efistub: Lower default log level

[PATCH] efistub: Lower default log level

[Aaron Kling via B4 Relay]

From: Aaron Kling <webgeek1234@gmail.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@kernel.org>
Signed-off-by: Aaron Kling <webgeek1234@gmail.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@gmail.com>

Re: [PATCH] efistub: Lower default log level

[Aaron Kling]

On Tue, Jul 8, 2025 at 2:30 AM Aaron Kling via B4 Relay
<devnull+webgeek1234.gmail.com@kernel.org> wrote:
>
> From: Aaron Kling <webgeek1234@gmail.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@kernel.org>
> Signed-off-by: Aaron Kling <webgeek1234@gmail.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@gmail.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.

Sincerely,
Aaron

[0] https://lore.kernel.org/all/CAMj1kXFKSrVx4SO_T8sHU=4hie8pjk8CUWQDV8oh+bz=xMn4rw@mail.gmail.com/

Re: [PATCH] efistub: Lower default log level

[Ard Biesheuvel]

On Tue, 8 Jul 2025 at 17:31, Aaron Kling <webgeek1234@gmail.com> wrote:
>
> On Tue, Jul 8, 2025 at 2:30 AM Aaron Kling via B4 Relay
> <devnull+webgeek1234.gmail.com@kernel.org> wrote:
> >
> > From: Aaron Kling <webgeek1234@gmail.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@kernel.org>
> > Signed-off-by: Aaron Kling <webgeek1234@gmail.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@gmail.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.

> [0] https://lore.kernel.org/all/CAMj1kXFKSrVx4SO_T8sHU=4hie8pjk8CUWQDV8oh+bz=xMn4rw@mail.gmail.com/

Re: [PATCH] efistub: Lower default log level

[Jan Kiszka]

On 15.07.25 03:35, Ard Biesheuvel wrote:
> On Tue, 8 Jul 2025 at 17:31, Aaron Kling <webgeek1234@gmail.com> wrote:
>>
>> On Tue, Jul 8, 2025 at 2:30 AM Aaron Kling via B4 Relay
>> <devnull+webgeek1234.gmail.com@kernel.org> wrote:
>>>
>>> From: Aaron Kling <webgeek1234@gmail.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@kernel.org>
>>> Signed-off-by: Aaron Kling <webgeek1234@gmail.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@gmail.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.

Jan

[1]
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/firmware/efi/libstub/secureboot.c?id=dfd4b508c8c6106083698a0dd5e35aecc7c48725#n60

-- 
Siemens AG, Foundational Technologies
Linux Expert Center

Re: [PATCH] efistub: Lower default log level

[Ard Biesheuvel]

On Sat, 16 Aug 2025 at 16:52, Jan Kiszka <jan.kiszka@siemens.com> wrote:
>
> On 15.07.25 03:35, Ard Biesheuvel wrote:
> > On Tue, 8 Jul 2025 at 17:31, Aaron Kling <webgeek1234@gmail.com> wrote:
> >>
> >> On Tue, Jul 8, 2025 at 2:30 AM Aaron Kling via B4 Relay
> >> <devnull+webgeek1234.gmail.com@kernel.org> wrote:
> >>>
> >>> From: Aaron Kling <webgeek1234@gmail.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@kernel.org>
> >>> Signed-off-by: Aaron Kling <webgeek1234@gmail.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@gmail.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?

Re: [PATCH] efistub: Lower default log level

[Jan Kiszka]

On 24.08.25 02:31, Ard Biesheuvel wrote:
> On Sat, 16 Aug 2025 at 16:52, Jan Kiszka <jan.kiszka@siemens.com> wrote:
>>
>> On 15.07.25 03:35, Ard Biesheuvel wrote:
>>> On Tue, 8 Jul 2025 at 17:31, Aaron Kling <webgeek1234@gmail.com> wrote:
>>>>
>>>> On Tue, Jul 8, 2025 at 2:30 AM Aaron Kling via B4 Relay
>>>> <devnull+webgeek1234.gmail.com@kernel.org> wrote:
>>>>>
>>>>> From: Aaron Kling <webgeek1234@gmail.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@kernel.org>
>>>>> Signed-off-by: Aaron Kling <webgeek1234@gmail.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@gmail.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?

Yes, also because it affects the kernel even more. I'm looking for
"efi=info".

I don't get the reason behind this change anymore as well. If you have a
splash screen shown, weren't you booting with "quiet" before already,
thus also without any stub messages?

Jan

-- 
Siemens AG, Foundational Technologies
Linux Expert Center

Re: [PATCH] efistub: Lower default log level

[Ard Biesheuvel]

On Sun, 24 Aug 2025 at 16:47, Jan Kiszka <jan.kiszka@siemens.com> wrote:
>
> On 24.08.25 02:31, Ard Biesheuvel wrote:
> > On Sat, 16 Aug 2025 at 16:52, Jan Kiszka <jan.kiszka@siemens.com> wrote:
> >>
> >> On 15.07.25 03:35, Ard Biesheuvel wrote:
> >>> On Tue, 8 Jul 2025 at 17:31, Aaron Kling <webgeek1234@gmail.com> wrote:
> >>>>
> >>>> On Tue, Jul 8, 2025 at 2:30 AM Aaron Kling via B4 Relay
> >>>> <devnull+webgeek1234.gmail.com@kernel.org> wrote:
> >>>>>
> >>>>> From: Aaron Kling <webgeek1234@gmail.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@kernel.org>
> >>>>> Signed-off-by: Aaron Kling <webgeek1234@gmail.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@gmail.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?
>
> Yes, also because it affects the kernel even more. I'm looking for
> "efi=info".
>
> I don't get the reason behind this change anymore as well. If you have a
> splash screen shown, weren't you booting with "quiet" before already,
> thus also without any stub messages?
>

Yeah, good point. IIRC that came up in the discussion but I can't
remember the motivation so it can't have been very convincing.

So should we just revert this change?

Re: [PATCH] efistub: Lower default log level

[Aaron Kling]

On Mon, Aug 25, 2025 at 5:44 AM Ard Biesheuvel <ardb@kernel.org> wrote:
>
> On Sun, 24 Aug 2025 at 16:47, Jan Kiszka <jan.kiszka@siemens.com> wrote:
> >
> > On 24.08.25 02:31, Ard Biesheuvel wrote:
> > > On Sat, 16 Aug 2025 at 16:52, Jan Kiszka <jan.kiszka@siemens.com> wrote:
> > >>
> > >> On 15.07.25 03:35, Ard Biesheuvel wrote:
> > >>> On Tue, 8 Jul 2025 at 17:31, Aaron Kling <webgeek1234@gmail.com> wrote:
> > >>>>
> > >>>> On Tue, Jul 8, 2025 at 2:30 AM Aaron Kling via B4 Relay
> > >>>> <devnull+webgeek1234.gmail.com@kernel.org> wrote:
> > >>>>>
> > >>>>> From: Aaron Kling <webgeek1234@gmail.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@kernel.org>
> > >>>>> Signed-off-by: Aaron Kling <webgeek1234@gmail.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@gmail.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?
> >
> > Yes, also because it affects the kernel even more. I'm looking for
> > "efi=info".
> >
> > I don't get the reason behind this change anymore as well. If you have a
> > splash screen shown, weren't you booting with "quiet" before already,
> > thus also without any stub messages?
> >
>
> Yeah, good point. IIRC that came up in the discussion but I can't
> remember the motivation so it can't have been very convincing.
>
> So should we just revert this change?

I'd prefer not to have to set quiet to get a clean splash screen. That
doesn't seem like an unreasonable expectation, getting default
non-debug logs and not having stuff written on top of the splash
image. But if this needs to be reverted, It would be nice to have an
option like the original patch which allowed setting the efi loglevel
separately. Or perhaps leave this as is and add the option to turn up
the efi loglevel independently.

Aaron

Re: [PATCH] efistub: Lower default log level

[Ard Biesheuvel]

On Tue, 26 Aug 2025 at 02:34, Aaron Kling <webgeek1234@gmail.com> wrote:
>
> On Mon, Aug 25, 2025 at 5:44 AM Ard Biesheuvel <ardb@kernel.org> wrote:
> >
> > On Sun, 24 Aug 2025 at 16:47, Jan Kiszka <jan.kiszka@siemens.com> wrote:
> > >
> > > On 24.08.25 02:31, Ard Biesheuvel wrote:
> > > > On Sat, 16 Aug 2025 at 16:52, Jan Kiszka <jan.kiszka@siemens.com> wrote:
> > > >>
> > > >> On 15.07.25 03:35, Ard Biesheuvel wrote:
> > > >>> On Tue, 8 Jul 2025 at 17:31, Aaron Kling <webgeek1234@gmail.com> wrote:
> > > >>>>
> > > >>>> On Tue, Jul 8, 2025 at 2:30 AM Aaron Kling via B4 Relay
> > > >>>> <devnull+webgeek1234.gmail.com@kernel.org> wrote:
> > > >>>>>
> > > >>>>> From: Aaron Kling <webgeek1234@gmail.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@kernel.org>
> > > >>>>> Signed-off-by: Aaron Kling <webgeek1234@gmail.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@gmail.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?
> > >
> > > Yes, also because it affects the kernel even more. I'm looking for
> > > "efi=info".
> > >
> > > I don't get the reason behind this change anymore as well. If you have a
> > > splash screen shown, weren't you booting with "quiet" before already,
> > > thus also without any stub messages?
> > >
> >
> > Yeah, good point. IIRC that came up in the discussion but I can't
> > remember the motivation so it can't have been very convincing.
> >
> > So should we just revert this change?
>
> I'd prefer not to have to set quiet to get a clean splash screen. That
> doesn't seem like an unreasonable expectation, getting default
> non-debug logs and not having stuff written on top of the splash
> image.

Perhaps you could remind us why this only applies to the efistub
output, and having the output of the kernel itself corrupting the
splash screen is fine?

> But if this needs to be reverted, It would be nice to have an
> option like the original patch which allowed setting the efi loglevel
> separately. Or perhaps leave this as is and add the option to turn up
> the efi loglevel independently.
>

Let's go back to the beginning and figure out to which problem this is
the solution.

Re: [PATCH] efistub: Lower default log level

[Aaron Kling]

On Mon, Aug 25, 2025 at 4:28 PM Ard Biesheuvel <ardb@kernel.org> wrote:
>
> On Tue, 26 Aug 2025 at 02:34, Aaron Kling <webgeek1234@gmail.com> wrote:
> >
> > On Mon, Aug 25, 2025 at 5:44 AM Ard Biesheuvel <ardb@kernel.org> wrote:
> > >
> > > On Sun, 24 Aug 2025 at 16:47, Jan Kiszka <jan.kiszka@siemens.com> wrote:
> > > >
> > > > On 24.08.25 02:31, Ard Biesheuvel wrote:
> > > > > On Sat, 16 Aug 2025 at 16:52, Jan Kiszka <jan.kiszka@siemens.com> wrote:
> > > > >>
> > > > >> On 15.07.25 03:35, Ard Biesheuvel wrote:
> > > > >>> On Tue, 8 Jul 2025 at 17:31, Aaron Kling <webgeek1234@gmail.com> wrote:
> > > > >>>>
> > > > >>>> On Tue, Jul 8, 2025 at 2:30 AM Aaron Kling via B4 Relay
> > > > >>>> <devnull+webgeek1234.gmail.com@kernel.org> wrote:
> > > > >>>>>
> > > > >>>>> From: Aaron Kling <webgeek1234@gmail.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@kernel.org>
> > > > >>>>> Signed-off-by: Aaron Kling <webgeek1234@gmail.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@gmail.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?
> > > >
> > > > Yes, also because it affects the kernel even more. I'm looking for
> > > > "efi=info".
> > > >
> > > > I don't get the reason behind this change anymore as well. If you have a
> > > > splash screen shown, weren't you booting with "quiet" before already,
> > > > thus also without any stub messages?
> > > >
> > >
> > > Yeah, good point. IIRC that came up in the discussion but I can't
> > > remember the motivation so it can't have been very convincing.
> > >
> > > So should we just revert this change?
> >
> > I'd prefer not to have to set quiet to get a clean splash screen. That
> > doesn't seem like an unreasonable expectation, getting default
> > non-debug logs and not having stuff written on top of the splash
> > image.
>
> Perhaps you could remind us why this only applies to the efistub
> output, and having the output of the kernel itself corrupting the
> splash screen is fine?

I'm not greatly knowledgeable about the efi standard and what's
happening under the hood, so I will just speak to what I saw in my use
case. I'm working on Nvidia Tegra devices, newer generations of which
use EDK2 as the last stage bootloader. The target os is Android, which
has a pretty strictly controlled defconfig. Prior to this change, the
kernel efistub logs were getting passed to the efi impl, which was
then printing those lines to the display. The kernel logs were not
being printed to the screen, as none of the console drivers were
enabled to do so. So after this change, regardless of the kernel log
level, the boot splash will remain untouched until the kernel display
driver takes over the display and the os renders to it. Because no
efistub log lines are being printed.

Aaron

Re: [PATCH] efistub: Lower default log level

[Jan Kiszka]

On 26.08.25 00:09, Aaron Kling wrote:
> On Mon, Aug 25, 2025 at 4:28 PM Ard Biesheuvel <ardb@kernel.org> wrote:
>>
>> On Tue, 26 Aug 2025 at 02:34, Aaron Kling <webgeek1234@gmail.com> wrote:
>>>
>>> On Mon, Aug 25, 2025 at 5:44 AM Ard Biesheuvel <ardb@kernel.org> wrote:
>>>>
>>>> On Sun, 24 Aug 2025 at 16:47, Jan Kiszka <jan.kiszka@siemens.com> wrote:
>>>>>
>>>>> On 24.08.25 02:31, Ard Biesheuvel wrote:
>>>>>> On Sat, 16 Aug 2025 at 16:52, Jan Kiszka <jan.kiszka@siemens.com> wrote:
>>>>>>>
>>>>>>> On 15.07.25 03:35, Ard Biesheuvel wrote:
>>>>>>>> On Tue, 8 Jul 2025 at 17:31, Aaron Kling <webgeek1234@gmail.com> wrote:
>>>>>>>>>
>>>>>>>>> On Tue, Jul 8, 2025 at 2:30 AM Aaron Kling via B4 Relay
>>>>>>>>> <devnull+webgeek1234.gmail.com@kernel.org> wrote:
>>>>>>>>>>
>>>>>>>>>> From: Aaron Kling <webgeek1234@gmail.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@kernel.org>
>>>>>>>>>> Signed-off-by: Aaron Kling <webgeek1234@gmail.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@gmail.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?
>>>>>
>>>>> Yes, also because it affects the kernel even more. I'm looking for
>>>>> "efi=info".
>>>>>
>>>>> I don't get the reason behind this change anymore as well. If you have a
>>>>> splash screen shown, weren't you booting with "quiet" before already,
>>>>> thus also without any stub messages?
>>>>>
>>>>
>>>> Yeah, good point. IIRC that came up in the discussion but I can't
>>>> remember the motivation so it can't have been very convincing.
>>>>
>>>> So should we just revert this change?
>>>
>>> I'd prefer not to have to set quiet to get a clean splash screen. That
>>> doesn't seem like an unreasonable expectation, getting default
>>> non-debug logs and not having stuff written on top of the splash
>>> image.
>>
>> Perhaps you could remind us why this only applies to the efistub
>> output, and having the output of the kernel itself corrupting the
>> splash screen is fine?
> 
> I'm not greatly knowledgeable about the efi standard and what's
> happening under the hood, so I will just speak to what I saw in my use
> case. I'm working on Nvidia Tegra devices, newer generations of which
> use EDK2 as the last stage bootloader. The target os is Android, which
> has a pretty strictly controlled defconfig. Prior to this change, the
> kernel efistub logs were getting passed to the efi impl, which was
> then printing those lines to the display. The kernel logs were not
> being printed to the screen, as none of the console drivers were
> enabled to do so. So after this change, regardless of the kernel log
> level, the boot splash will remain untouched until the kernel display
> driver takes over the display and the os renders to it. Because no
> efistub log lines are being printed.
> 

That makes sense now, and surely don't mind having some build-time or
runtime configuration switch that allow to tune the system into such
settings. It's just not so nice to take away the freedom of full-scale
loglevel control from the efistub.

Jan

-- 
Siemens AG, Foundational Technologies
Linux Expert Center

Re: [PATCH] efistub: Lower default log level

[Ard Biesheuvel]

On Tue, 26 Aug 2025 at 09:23, Jan Kiszka <jan.kiszka@siemens.com> wrote:
>
> On 26.08.25 00:09, Aaron Kling wrote:
> > On Mon, Aug 25, 2025 at 4:28 PM Ard Biesheuvel <ardb@kernel.org> wrote:
> >>
> >> On Tue, 26 Aug 2025 at 02:34, Aaron Kling <webgeek1234@gmail.com> wrote:
> >>>
> >>> On Mon, Aug 25, 2025 at 5:44 AM Ard Biesheuvel <ardb@kernel.org> wrote:
> >>>>
> >>>> On Sun, 24 Aug 2025 at 16:47, Jan Kiszka <jan.kiszka@siemens.com> wrote:
> >>>>>
> >>>>> On 24.08.25 02:31, Ard Biesheuvel wrote:
> >>>>>> On Sat, 16 Aug 2025 at 16:52, Jan Kiszka <jan.kiszka@siemens.com> wrote:
> >>>>>>>
> >>>>>>> On 15.07.25 03:35, Ard Biesheuvel wrote:
> >>>>>>>> On Tue, 8 Jul 2025 at 17:31, Aaron Kling <webgeek1234@gmail.com> wrote:
> >>>>>>>>>
> >>>>>>>>> On Tue, Jul 8, 2025 at 2:30 AM Aaron Kling via B4 Relay
> >>>>>>>>> <devnull+webgeek1234.gmail.com@kernel.org> wrote:
> >>>>>>>>>>
> >>>>>>>>>> From: Aaron Kling <webgeek1234@gmail.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@kernel.org>
> >>>>>>>>>> Signed-off-by: Aaron Kling <webgeek1234@gmail.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@gmail.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?
> >>>>>
> >>>>> Yes, also because it affects the kernel even more. I'm looking for
> >>>>> "efi=info".
> >>>>>
> >>>>> I don't get the reason behind this change anymore as well. If you have a
> >>>>> splash screen shown, weren't you booting with "quiet" before already,
> >>>>> thus also without any stub messages?
> >>>>>
> >>>>
> >>>> Yeah, good point. IIRC that came up in the discussion but I can't
> >>>> remember the motivation so it can't have been very convincing.
> >>>>
> >>>> So should we just revert this change?
> >>>
> >>> I'd prefer not to have to set quiet to get a clean splash screen. That
> >>> doesn't seem like an unreasonable expectation, getting default
> >>> non-debug logs and not having stuff written on top of the splash
> >>> image.
> >>
> >> Perhaps you could remind us why this only applies to the efistub
> >> output, and having the output of the kernel itself corrupting the
> >> splash screen is fine?
> >
> > I'm not greatly knowledgeable about the efi standard and what's
> > happening under the hood, so I will just speak to what I saw in my use
> > case. I'm working on Nvidia Tegra devices, newer generations of which
> > use EDK2 as the last stage bootloader. The target os is Android, which
> > has a pretty strictly controlled defconfig. Prior to this change, the
> > kernel efistub logs were getting passed to the efi impl, which was
> > then printing those lines to the display. The kernel logs were not
> > being printed to the screen, as none of the console drivers were
> > enabled to do so. So after this change, regardless of the kernel log
> > level, the boot splash will remain untouched until the kernel display
> > driver takes over the display and the os renders to it. Because no
> > efistub log lines are being printed.
> >
>
> That makes sense now, and surely don't mind having some build-time or
> runtime configuration switch that allow to tune the system into such
> settings. It's just not so nice to take away the freedom of full-scale
> loglevel control from the efistub.
>

Yeah, that would be my fault, I guess. I suggested simplifying this to
the current approach.

Would it be sufficient to make the EFI stub loglevel a separate
compile time Kconfig option? I'd prefer that over adding more runtime
logic.

Re: [PATCH] efistub: Lower default log level

[Ard Biesheuvel]

On Tue, 26 Aug 2025 at 10:16, Ard Biesheuvel <ardb@kernel.org> wrote:
>
> On Tue, 26 Aug 2025 at 09:23, Jan Kiszka <jan.kiszka@siemens.com> wrote:
> >
> > On 26.08.25 00:09, Aaron Kling wrote:
> > > On Mon, Aug 25, 2025 at 4:28 PM Ard Biesheuvel <ardb@kernel.org> wrote:
> > >>
> > >> On Tue, 26 Aug 2025 at 02:34, Aaron Kling <webgeek1234@gmail.com> wrote:
> > >>>
> > >>> On Mon, Aug 25, 2025 at 5:44 AM Ard Biesheuvel <ardb@kernel.org> wrote:
> > >>>>
> > >>>> On Sun, 24 Aug 2025 at 16:47, Jan Kiszka <jan.kiszka@siemens.com> wrote:
> > >>>>>
> > >>>>> On 24.08.25 02:31, Ard Biesheuvel wrote:
> > >>>>>> On Sat, 16 Aug 2025 at 16:52, Jan Kiszka <jan.kiszka@siemens.com> wrote:
> > >>>>>>>
> > >>>>>>> On 15.07.25 03:35, Ard Biesheuvel wrote:
> > >>>>>>>> On Tue, 8 Jul 2025 at 17:31, Aaron Kling <webgeek1234@gmail.com> wrote:
> > >>>>>>>>>
> > >>>>>>>>> On Tue, Jul 8, 2025 at 2:30 AM Aaron Kling via B4 Relay
> > >>>>>>>>> <devnull+webgeek1234.gmail.com@kernel.org> wrote:
> > >>>>>>>>>>
> > >>>>>>>>>> From: Aaron Kling <webgeek1234@gmail.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@kernel.org>
> > >>>>>>>>>> Signed-off-by: Aaron Kling <webgeek1234@gmail.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@gmail.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?
> > >>>>>
> > >>>>> Yes, also because it affects the kernel even more. I'm looking for
> > >>>>> "efi=info".
> > >>>>>
> > >>>>> I don't get the reason behind this change anymore as well. If you have a
> > >>>>> splash screen shown, weren't you booting with "quiet" before already,
> > >>>>> thus also without any stub messages?
> > >>>>>
> > >>>>
> > >>>> Yeah, good point. IIRC that came up in the discussion but I can't
> > >>>> remember the motivation so it can't have been very convincing.
> > >>>>
> > >>>> So should we just revert this change?
> > >>>
> > >>> I'd prefer not to have to set quiet to get a clean splash screen. That
> > >>> doesn't seem like an unreasonable expectation, getting default
> > >>> non-debug logs and not having stuff written on top of the splash
> > >>> image.
> > >>
> > >> Perhaps you could remind us why this only applies to the efistub
> > >> output, and having the output of the kernel itself corrupting the
> > >> splash screen is fine?
> > >
> > > I'm not greatly knowledgeable about the efi standard and what's
> > > happening under the hood, so I will just speak to what I saw in my use
> > > case. I'm working on Nvidia Tegra devices, newer generations of which
> > > use EDK2 as the last stage bootloader. The target os is Android, which
> > > has a pretty strictly controlled defconfig. Prior to this change, the
> > > kernel efistub logs were getting passed to the efi impl, which was
> > > then printing those lines to the display. The kernel logs were not
> > > being printed to the screen, as none of the console drivers were
> > > enabled to do so. So after this change, regardless of the kernel log
> > > level, the boot splash will remain untouched until the kernel display
> > > driver takes over the display and the os renders to it. Because no
> > > efistub log lines are being printed.
> > >
> >
> > That makes sense now, and surely don't mind having some build-time or
> > runtime configuration switch that allow to tune the system into such
> > settings. It's just not so nice to take away the freedom of full-scale
> > loglevel control from the efistub.
> >
>
> Yeah, that would be my fault, I guess. I suggested simplifying this to
> the current approach.
>
> Would it be sufficient to make the EFI stub loglevel a separate
> compile time Kconfig option? I'd prefer that over adding more runtime
> logic.

Would the below work for you Aaron?

diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig
index eb1bff6968a5..f7552f36ab51 100644
--- a/drivers/firmware/efi/Kconfig
+++ b/drivers/firmware/efi/Kconfig
@@ -72,6 +72,11 @@ config EFI_RUNTIME_WRAPPERS
 config EFI_GENERIC_STUB
        bool

+config EFI_STUB_LOGLEVEL
+       int "Loglevel for the EFI stub console"
+       range 1 15
+       default CONSOLE_LOGLEVEL_DEFAULT
+
 config EFI_ZBOOT
        bool "Enable the generic EFI decompressor"
        depends on EFI_GENERIC_STUB && !ARM
diff --git a/drivers/firmware/efi/libstub/printk.c
b/drivers/firmware/efi/libstub/printk.c
index bc599212c05d..782d1330c1cc 100644
--- a/drivers/firmware/efi/libstub/printk.c
+++ b/drivers/firmware/efi/libstub/printk.c
@@ -5,13 +5,12 @@
 #include <linux/ctype.h>
 #include <linux/efi.h>
 #include <linux/kernel.h>
-#include <linux/kern_levels.h>
 #include <asm/efi.h>
 #include <asm/setup.h>

 #include "efistub.h"

-int efi_loglevel = LOGLEVEL_NOTICE;
+int efi_loglevel = CONFIG_EFI_STUB_LOGLEVEL;

 /**
  * efi_char16_puts() - Write a UCS-2 encoded string to the console

Re: [PATCH] efistub: Lower default log level

[Aaron Kling]

On Tue, Aug 26, 2025 at 7:43 AM Ard Biesheuvel <ardb@kernel.org> wrote:
>
> On Tue, 26 Aug 2025 at 10:16, Ard Biesheuvel <ardb@kernel.org> wrote:
> >
> > On Tue, 26 Aug 2025 at 09:23, Jan Kiszka <jan.kiszka@siemens.com> wrote:
> > >
> > > On 26.08.25 00:09, Aaron Kling wrote:
> > > > On Mon, Aug 25, 2025 at 4:28 PM Ard Biesheuvel <ardb@kernel.org> wrote:
> > > >>
> > > >> On Tue, 26 Aug 2025 at 02:34, Aaron Kling <webgeek1234@gmail.com> wrote:
> > > >>>
> > > >>> On Mon, Aug 25, 2025 at 5:44 AM Ard Biesheuvel <ardb@kernel.org> wrote:
> > > >>>>
> > > >>>> On Sun, 24 Aug 2025 at 16:47, Jan Kiszka <jan.kiszka@siemens.com> wrote:
> > > >>>>>
> > > >>>>> On 24.08.25 02:31, Ard Biesheuvel wrote:
> > > >>>>>> On Sat, 16 Aug 2025 at 16:52, Jan Kiszka <jan.kiszka@siemens.com> wrote:
> > > >>>>>>>
> > > >>>>>>> On 15.07.25 03:35, Ard Biesheuvel wrote:
> > > >>>>>>>> On Tue, 8 Jul 2025 at 17:31, Aaron Kling <webgeek1234@gmail.com> wrote:
> > > >>>>>>>>>
> > > >>>>>>>>> On Tue, Jul 8, 2025 at 2:30 AM Aaron Kling via B4 Relay
> > > >>>>>>>>> <devnull+webgeek1234.gmail.com@kernel.org> wrote:
> > > >>>>>>>>>>
> > > >>>>>>>>>> From: Aaron Kling <webgeek1234@gmail.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@kernel.org>
> > > >>>>>>>>>> Signed-off-by: Aaron Kling <webgeek1234@gmail.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@gmail.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?
> > > >>>>>
> > > >>>>> Yes, also because it affects the kernel even more. I'm looking for
> > > >>>>> "efi=info".
> > > >>>>>
> > > >>>>> I don't get the reason behind this change anymore as well. If you have a
> > > >>>>> splash screen shown, weren't you booting with "quiet" before already,
> > > >>>>> thus also without any stub messages?
> > > >>>>>
> > > >>>>
> > > >>>> Yeah, good point. IIRC that came up in the discussion but I can't
> > > >>>> remember the motivation so it can't have been very convincing.
> > > >>>>
> > > >>>> So should we just revert this change?
> > > >>>
> > > >>> I'd prefer not to have to set quiet to get a clean splash screen. That
> > > >>> doesn't seem like an unreasonable expectation, getting default
> > > >>> non-debug logs and not having stuff written on top of the splash
> > > >>> image.
> > > >>
> > > >> Perhaps you could remind us why this only applies to the efistub
> > > >> output, and having the output of the kernel itself corrupting the
> > > >> splash screen is fine?
> > > >
> > > > I'm not greatly knowledgeable about the efi standard and what's
> > > > happening under the hood, so I will just speak to what I saw in my use
> > > > case. I'm working on Nvidia Tegra devices, newer generations of which
> > > > use EDK2 as the last stage bootloader. The target os is Android, which
> > > > has a pretty strictly controlled defconfig. Prior to this change, the
> > > > kernel efistub logs were getting passed to the efi impl, which was
> > > > then printing those lines to the display. The kernel logs were not
> > > > being printed to the screen, as none of the console drivers were
> > > > enabled to do so. So after this change, regardless of the kernel log
> > > > level, the boot splash will remain untouched until the kernel display
> > > > driver takes over the display and the os renders to it. Because no
> > > > efistub log lines are being printed.
> > > >
> > >
> > > That makes sense now, and surely don't mind having some build-time or
> > > runtime configuration switch that allow to tune the system into such
> > > settings. It's just not so nice to take away the freedom of full-scale
> > > loglevel control from the efistub.
> > >
> >
> > Yeah, that would be my fault, I guess. I suggested simplifying this to
> > the current approach.
> >
> > Would it be sufficient to make the EFI stub loglevel a separate
> > compile time Kconfig option? I'd prefer that over adding more runtime
> > logic.
>
> Would the below work for you Aaron?
>
> diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig
> index eb1bff6968a5..f7552f36ab51 100644
> --- a/drivers/firmware/efi/Kconfig
> +++ b/drivers/firmware/efi/Kconfig
> @@ -72,6 +72,11 @@ config EFI_RUNTIME_WRAPPERS
>  config EFI_GENERIC_STUB
>         bool
>
> +config EFI_STUB_LOGLEVEL
> +       int "Loglevel for the EFI stub console"
> +       range 1 15
> +       default CONSOLE_LOGLEVEL_DEFAULT
> +
>  config EFI_ZBOOT
>         bool "Enable the generic EFI decompressor"
>         depends on EFI_GENERIC_STUB && !ARM
> diff --git a/drivers/firmware/efi/libstub/printk.c
> b/drivers/firmware/efi/libstub/printk.c
> index bc599212c05d..782d1330c1cc 100644
> --- a/drivers/firmware/efi/libstub/printk.c
> +++ b/drivers/firmware/efi/libstub/printk.c
> @@ -5,13 +5,12 @@
>  #include <linux/ctype.h>
>  #include <linux/efi.h>
>  #include <linux/kernel.h>
> -#include <linux/kern_levels.h>
>  #include <asm/efi.h>
>  #include <asm/setup.h>
>
>  #include "efistub.h"
>
> -int efi_loglevel = LOGLEVEL_NOTICE;
> +int efi_loglevel = CONFIG_EFI_STUB_LOGLEVEL;
>
>  /**
>   * efi_char16_puts() - Write a UCS-2 encoded string to the console

The only issue for me is that the Android defconfig is set by Google.
Specific devices build kernel modules in a device specific manner, but
the core kernel is fixed. And since efistub is =y, that means vendors
and third party projects like me cannot change this as a build time
config. This works for me only if I can convince Google to set the log
level lower in their defconfig. If this is what you wish to do, I can
suggest such a change to aosp once they fork the next lts.

Aaron