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ACPI: Add acpi=nospcr to disable ACPI SPCR as default console on ARM64

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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=nospcr to disable console in ACPI SPCR table as default
_serial_ console.

Signed-off-by: Liu Wei <liuwei09@cestc.cn>
Suggested-by: Prarit Bhargava <prarit@redhat.com>
Suggested-by: Will Deacon <will@kernel.org>
Suggested-by: Andrew Lunn <andrew@lunn.ch>
Reviewed-by: Hanjun Guo <guohanjun@huawei.com>
Reviewed-by: Prarit Bhargava <prarit@redhat.com>
Link: https://lore.kernel.org/r/20240625030504.58025-1-liuwei09@cestc.cn
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
This commit is contained in:
Liu Wei
2024-06-25 11:05:04 +08:00
committed by Catalin Marinas
parent bfe3f0df3e
commit f5a4af3c75
2 changed files with 24 additions and 4 deletions
Download Patch File Download Diff File Expand all files Collapse all files

10
Documentation/admin-guide/kernel-parameters.txt
View File

@@ -12,7 +12,7 @@
acpi= [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=off", "acpi=on" or
"acpi=force" are available
nospcr -- disable console in ACPI SPCR table as
default _serial_ console on ARM64
For ARM64, ONLY "acpi=off", "acpi=on", "acpi=force" or
"acpi=nospcr" are available
For RISCV64, ONLY "acpi=off", "acpi=on" or "acpi=force"
are available
See also Documentation/power/runtime_pm.rst, pci=noacpi

18
arch/arm64/kernel/acpi.c
View File

@@ -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;
static int __init parse_acpi(char *arg)
{
@@ -58,6 +59,8 @@ static int __init parse_acpi(char *arg)
param_acpi_on = true;
else if (strcmp(arg, "force") == 0) /* force ACPI to be enabled */
param_acpi_force = true;
else if (strcmp(arg, "nospcr") == 0) /* disable SPCR as default console */
param_acpi_nospcr = true;
else
return -EINVAL; /* Core will print when we return error */
@@ -237,7 +240,20 @@ done:
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
* behaviour, use acpi=nospcr 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);
}