Re: [PATCH] ACPICA: Add ACPI_MSG_DEBUG to set KERN_DEBUG for debug output

[Mario Limonciello <superm1@kernel.org>]

On 9/9/26 10:50, Rafael J. Wysocki (Intel) wrote:
> On Mon, Aug 31, 2026 at 7:34 AM Mario Limonciello (AMD)
> <superm1@kernel.org> wrote:
>>
>> acpi_debug_print() emits ACPI debug output using multi-part
>> acpi_os_printf() and acpi_os_vprintf() calls without any loglevel
>> prefix.
>>
>> When acpi_os_vprintf() processes a chunk without a loglevel prefix
>> (printk_get_level() returns 0), it prepends KERN_CONT. Because the initial
>> header chunk lacks a loglevel prefix, it either attaches to a preceding
>> unfinalized log message (inheriting its level) or, when split across
>> printk buffer records, falls back to the default message loglevel rather
>> than KERN_DEBUG. This can cause dmesg to misinterpret and colorize debug
>> messages as errors.
>>
>> Define ACPI_MSG_DEBUG as KERN_DEBUG in aclinux.h (with an empty fallback
>> in acutils.h for ACPICA OS-independence) and prefix debug message headers
>> and context switch output in acpi_debug_print() with ACPI_MSG_DEBUG so
>> that printk records are properly tagged with KERN_DEBUG.
>>
>> Signed-off-by: Mario Limonciello (AMD) <superm1@kernel.org>
>> ---
>> Given this is purely for Linux - it's not obvious to me if it should
>> go upstream to ACPICA or directly to Linux.  Sending here for now.
> 
> Defining ACPI_MSG_DEBUG upstream would make sense in my view, so why
> don't you submit it there?

OK - No problem.  I've submitted there.

https://github.com/open-acpica/acpica/pull/1231

> 
>> ---
>>   drivers/acpi/acpica/acutils.h   | 3 +++
>>   drivers/acpi/acpica/utdebug.c   | 4 ++--
>>   include/acpi/platform/aclinux.h | 1 +
>>   3 files changed, 6 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/acpi/acpica/acutils.h b/drivers/acpi/acpica/acutils.h
>> index 9049bfee409c4..766a3080b5ea1 100644
>> --- a/drivers/acpi/acpica/acutils.h
>> +++ b/drivers/acpi/acpica/acutils.h
>> @@ -100,6 +100,9 @@ extern const char *acpi_gbl_clock_input_scale[];
>>   #ifndef ACPI_MSG_BIOS_WARNING
>>   #define ACPI_MSG_BIOS_WARNING   "Firmware Warning (ACPI): "
>>   #endif
>> +#ifndef ACPI_MSG_DEBUG
>> +#define ACPI_MSG_DEBUG          ""
>> +#endif
>>
>>   /*
>>    * Common message suffix
>> diff --git a/drivers/acpi/acpica/utdebug.c b/drivers/acpi/acpica/utdebug.c
>> index a31e07400c34d..1f2cab491637f 100644
>> --- a/drivers/acpi/acpica/utdebug.c
>> +++ b/drivers/acpi/acpica/utdebug.c
>> @@ -156,7 +156,7 @@ acpi_debug_print(u32 requested_debug_level,
>>          if (thread_id != acpi_gbl_previous_thread_id) {
>>                  if (ACPI_LV_THREADS & acpi_dbg_level) {
>>                          acpi_os_printf
>> -                           ("\n**** Context Switch from TID %u to TID %u ****\n\n",
>> +                           (ACPI_MSG_DEBUG "\n**** Context Switch from TID %u to TID %u ****\n\n",
>>                               (u32)acpi_gbl_previous_thread_id, (u32)thread_id);
>>                  }
>>
>> @@ -168,7 +168,7 @@ acpi_debug_print(u32 requested_debug_level,
>>           * Display the module name, current line number, thread ID (if requested),
>>           * current procedure nesting level, and the current procedure name
>>           */
>> -       acpi_os_printf("%9s-%04d ", module_name, line_number);
>> +       acpi_os_printf(ACPI_MSG_DEBUG "%9s-%04d ", module_name, line_number);
>>
>>   #ifdef ACPI_APPLICATION
>>          /*
>> diff --git a/include/acpi/platform/aclinux.h b/include/acpi/platform/aclinux.h
>> index 9b30bb9ed711c..5e2ed5e79d3b8 100644
>> --- a/include/acpi/platform/aclinux.h
>> +++ b/include/acpi/platform/aclinux.h
>> @@ -169,6 +169,7 @@
>>
>>   #define ACPI_MSG_BIOS_ERROR     KERN_ERR "ACPI BIOS Error (bug): "
>>   #define ACPI_MSG_BIOS_WARNING   KERN_WARNING "ACPI BIOS Warning (bug): "
>> +#define ACPI_MSG_DEBUG          KERN_DEBUG
>>
>>   /*
>>    * Linux wants to use designated initializers for function pointer structs.
>> --
>> 2.53.0
>>