From nobody Wed Dec 17 17:43:22 2025 Received: from smtp.cecloud.com (unknown [1.203.97.240]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 198814AEFA for ; Tue, 25 Jun 2024 03:05:18 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=1.203.97.240 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719284723; cv=none; b=ZQ9SCxkaoQ655mLXr2ln/RuDjnikuUrjlJFysUOsA3EGrNSDCZru2KHz1oKO5ibYdCN37GEwx1LoU+92dSy4QQ2d425syQ8K8JS7RSh1mvyzdSmrdkzeWGu7AwtYdL761m4WyznjSpI1Gxm0ixBuaMaYvys44VJvxhuNZs0HQkU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1719284723; c=relaxed/simple; bh=QMK1XmhKnmgYUTUZ9V/V43jdFuZ3zPgdogMXw3AYJiU=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=rtNY6Z/lt+2yZRU+8mM5mpAOSb45q4NZ9Adf6Au1y6jh4HToqn0rtQ4acumK4NhUGuzqk8Davpyv5Ws8Njd2MXkGjMF07gtV3LCBaXiUyH90tpoNWvgFBzr7h3ba7cg1NIfvxc+ycIvv4rdMizwQZABhP702m4xMvwIA4sWKP3k= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=cestc.cn; spf=pass smtp.mailfrom=cestc.cn; arc=none smtp.client-ip=1.203.97.240 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=cestc.cn Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=cestc.cn Received: from localhost (localhost [127.0.0.1]) by smtp.cecloud.com (Postfix) with ESMTP id 568A9900114; Tue, 25 Jun 2024 11:05:17 +0800 (CST) X-MAIL-GRAY: 0 X-MAIL-DELIVERY: 1 X-SKE-CHECKED: 1 X-ANTISPAM-LEVEL: 2 Received: from localhost.localdomain (unknown [111.48.69.245]) by smtp.cecloud.com (postfix) whith ESMTP id P1340310T281473223422320S1719284716218537_; Tue, 25 Jun 2024 11:05:17 +0800 (CST) X-IP-DOMAINF: 1 X-RL-SENDER: liuwei09@cestc.cn X-SENDER: liuwei09@cestc.cn X-LOGIN-NAME: liuwei09@cestc.cn X-FST-TO: liuwei09@cestc.cn X-RCPT-COUNT: 7 X-LOCAL-RCPT-COUNT: 1 X-MUTI-DOMAIN-COUNT: 0 X-SENDER-IP: 111.48.69.245 X-ATTACHMENT-NUM: 0 X-UNIQUE-TAG: X-System-Flag: 0 From: Liu Wei To: liuwei09@cestc.cn, will@kernel.org Cc: catalin.marinas@arm.com, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, prarit@redhat.com, Andrew Lunn Subject: [PATCH v4] ACPI: Add acpi=nospcr to disable ACPI SPCR as default console on ARM64 Date: Tue, 25 Jun 2024 11:05:04 +0800 Message-ID: <20240625030504.58025-1-liuwei09@cestc.cn> X-Mailer: git-send-email 2.42.1 In-Reply-To: <20240530015332.7305-1-liuwei09@cestc.cn> References: <20240530015332.7305-1-liuwei09@cestc.cn> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" For varying privacy and security reasons, sometimes we would like to completely silence the _serial_ console, and only enable it when needed. But there are many existing systems that depend on this _serial_ console, so add acpi=3Dnospcr to disable console in ACPI SPCR table as default _serial_ console. Signed-off-by: Liu Wei Suggested-by: Prarit Bhargava Suggested-by: Will Deacon Suggested-by: Andrew Lunn Reviewed-by: Hanjun Guo Reviewed-by: Prarit Bhargava --- v2: Add a config option suggested by Prarit v3: Use cmdline acpi=3Dnospcr instead of config v4: Some description in comment or document --- .../admin-guide/kernel-parameters.txt | 10 +++++++--- arch/arm64/kernel/acpi.c | 18 +++++++++++++++++- 2 files changed, 24 insertions(+), 4 deletions(-) diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentatio= n/admin-guide/kernel-parameters.txt index 11e57ba2985c..6814ff7ae446 100644 --- a/Documentation/admin-guide/kernel-parameters.txt +++ b/Documentation/admin-guide/kernel-parameters.txt @@ -12,7 +12,7 @@ acpi=3D [HW,ACPI,X86,ARM64,RISCV64,EARLY] Advanced Configuration and Power Interface Format: { force | on | off | strict | noirq | rsdt | - copy_dsdt } + copy_dsdt | nospcr } force -- enable ACPI if default was off on -- enable ACPI but allow fallback to DT [arm64,riscv64] off -- disable ACPI if default was on @@ -21,8 +21,12 @@ strictly ACPI specification compliant. rsdt -- prefer RSDT over (default) XSDT copy_dsdt -- copy DSDT to memory - For ARM64 and RISCV64, ONLY "acpi=3Doff", "acpi=3Don" or - "acpi=3Dforce" are available + nospcr -- disable console in ACPI SPCR table as + default _serial_ console on ARM64 + For ARM64, ONLY "acpi=3Doff", "acpi=3Don", "acpi=3Dforce" or + "acpi=3Dnospcr" are available + For RISCV64, ONLY "acpi=3Doff", "acpi=3Don" or "acpi=3Dforce" + are available =20 See also Documentation/power/runtime_pm.rst, pci=3Dnoacpi =20 diff --git a/arch/arm64/kernel/acpi.c b/arch/arm64/kernel/acpi.c index e0e7b93c16cc..55757d8884d4 100644 --- a/arch/arm64/kernel/acpi.c +++ b/arch/arm64/kernel/acpi.c @@ -45,6 +45,7 @@ EXPORT_SYMBOL(acpi_pci_disabled); static bool param_acpi_off __initdata; static bool param_acpi_on __initdata; static bool param_acpi_force __initdata; +static bool param_acpi_nospcr __initdata; =20 static int __init parse_acpi(char *arg) { @@ -58,6 +59,8 @@ static int __init parse_acpi(char *arg) param_acpi_on =3D true; else if (strcmp(arg, "force") =3D=3D 0) /* force ACPI to be enabled */ param_acpi_force =3D true; + else if (strcmp(arg, "nospcr") =3D=3D 0) /* disable SPCR as default conso= le */ + param_acpi_nospcr =3D true; else return -EINVAL; /* Core will print when we return error */ =20 @@ -237,7 +240,20 @@ void __init acpi_boot_table_init(void) acpi_put_table(facs); } #endif - acpi_parse_spcr(earlycon_acpi_spcr_enable, true); + + /* + * For varying privacy and security reasons, sometimes need + * to completely silence the serial console output, and only + * enable it when needed. + * But there are many existing systems that depend on this + * behavior, use acpi=3Dnospcr to disable console in ACPI SPCR + * table as default serial console. + */ + acpi_parse_spcr(earlycon_acpi_spcr_enable, + !param_acpi_nospcr); + pr_info("Use ACPI SPCR as default console: %s\n", + param_acpi_nospcr ? "No" : "Yes"); + if (IS_ENABLED(CONFIG_ACPI_BGRT)) acpi_table_parse(ACPI_SIG_BGRT, acpi_parse_bgrt); } --=20 2.42.1