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From: Peter Jones <>
To: Ard Biesheuvel <>
	Peter Jones <>
Subject: [PATCH] Make it possible to disable efivar_ssdt entirely
Date: Mon, 15 Jun 2020 16:24:08 -0400	[thread overview]
Message-ID: <> (raw)

In most cases, such as CONFIG_ACPI_CUSTOM_DSDT and
CONFIG_ACPI_TABLE_UPGRADE, boot-time modifications to firmware tables
are tied to specific Kconfig options.  Currently this is not the case
for modifying the ACPI SSDT via the efivar_ssdt kernel command line
option and associated EFI variable.

This patch adds CONFIG_EFI_CUSTOM_SSDT_OVERLAYS, which defaults
disabled, in order to allow enabling or disabling that feature during
the build.

Signed-off-by: Peter Jones <>
 drivers/firmware/efi/efi.c   |  2 +-
 drivers/firmware/efi/Kconfig | 11 +++++++++++
 2 files changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index 48d0188936c..4b12a598ccf 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -192,7 +192,7 @@ static void generic_ops_unregister(void)
 static char efivar_ssdt[EFIVAR_SSDT_NAME_MAX] __initdata;
 static int __init efivar_ssdt_setup(char *str)
diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig
index 6b38f9e5d20..fe433f76b03 100644
--- a/drivers/firmware/efi/Kconfig
+++ b/drivers/firmware/efi/Kconfig
@@ -278,3 +278,14 @@ config EFI_EARLYCON
 	depends on SERIAL_EARLYCON && !ARM && !IA64
+	bool "Load custom ACPI SSDT overlay from an EFI variable"
+	depends on EFI_VARS
+	help
+	  Allow loading of an ACPI SSDT overlay from an EFI variable specified
+	  by a kernel command line option.
+	  See Documentation/admin-guide/acpi/ssdt-overlays.rst for more
+	  information.

             reply	other threads:[~2020-06-15 20:24 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-15 20:24 Peter Jones [this message]
2020-06-15 22:47 ` [PATCH] Make it possible to disable efivar_ssdt entirely Ard Biesheuvel
2020-06-17  9:01   ` Ard Biesheuvel

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