linux-kernel - [PATCH v2 0/2] ACPI: Improve SPCR handling and messaging on SPCR-less systems

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Message-ID: <20250620131309.126555-1-me@linux.beauty>
Date: Fri, 20 Jun 2025 21:13:06 +0800
From: Li Chen <me@...ux.beauty>
To: Hanjun Guo <guohanjun@...wei.com>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will@...nel.org>,
	"Rafael J . Wysocki" <rafael@...nel.org>,
	Len Brown <lenb@...nel.org>,
	Liu Wei <liuwei09@...tc.cn>,
	Ryan Roberts <ryan.roberts@....com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Jonathan Cameron <Jonathan.Cameron@...wei.com>,
	Sudeep Holla <sudeep.holla@....com>,
	linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org,
	linux-acpi@...r.kernel.org
Subject: [PATCH v2 0/2] ACPI: Improve SPCR handling and messaging on SPCR-less systems

From: Li Chen <chenl311@...natelecom.cn>

From: Li Chen <chenl311@...natelecom.cn>

This small series improves the kernel behavior and output when the ACPI SPCR
table is not present or not supported.

Currently, even on systems that completely lack an SPCR table, the kernel prints:
"Use ACPI SPCR as default console: Yes"

This may mislead users into thinking an SPCR table exists
when in fact there is no such table at all. This series addresses this in two steps:

Patch 1 ensures that acpi_parse_spcr() returns -ENODEV if CONFIG_ACPI_SPCR_TABLE is disabled.

Patch 2 updates arm64 acpi_boot_table_init() to only print the Yes
if acpi_parse_spcr() succeeds.

This results in cleaner and more accurate boot logs on ARM64.

Tested on both SPCR-enabled and SPCR-less qemu-system arm64 virt platform. [1]

Changelog:
v2: refine the printk message logic as suggested by Hanjun Guo. [2]

[1]: https://patchew.org/QEMU/20250528105404.457729-1-me@linux.beauty/
[2]: https://www.spinics.net/lists/kernel/msg5730585.html

Li Chen (2):
  ACPI: Return -ENODEV from acpi_parse_spcr() when SPCR support is
    disabled
  ACPI: Suppress misleading SPCR console message when SPCR table is
    absent

 arch/arm64/kernel/acpi.c | 10 +++++++---
 include/linux/acpi.h     |  2 +-
 2 files changed, 8 insertions(+), 4 deletions(-)

-- 
2.49.0