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* [PATCH] Make it possible to disable efivar_ssdt entirely
@ 2020-06-15 20:24 Peter Jones
  2020-06-15 22:47 ` Ard Biesheuvel
  2020-06-19 16:45 ` [tip: efi/urgent] efi: " tip-bot2 for Peter Jones
  0 siblings, 2 replies; 4+ messages in thread
From: Peter Jones @ 2020-06-15 20:24 UTC (permalink / raw)
  To: Ard Biesheuvel; +Cc: linux-efi, linux-kernel, Peter Jones

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 <pjones@redhat.com>
---
 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)
 	efivars_unregister(&generic_efivars);
 }
 
-#if IS_ENABLED(CONFIG_ACPI)
+#if IS_ENABLED(CONFIG_EFI_CUSTOM_SSDT_OVERLAYS)
 #define EFIVAR_SSDT_NAME_MAX	16
 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
 	select FONT_SUPPORT
 	select ARCH_USE_MEMREMAP_PROT
+
+config EFI_CUSTOM_SSDT_OVERLAYS
+	bool "Load custom ACPI SSDT overlay from an EFI variable"
+	depends on EFI_VARS
+	default ACPI_TABLE_UPGRADE
+	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.
-- 
2.26.2


^ permalink raw reply	[flat|nested] 4+ messages in thread

end of thread, other threads:[~2020-06-19 16:46 UTC | newest]

Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2020-06-15 20:24 [PATCH] Make it possible to disable efivar_ssdt entirely Peter Jones
2020-06-15 22:47 ` Ard Biesheuvel
2020-06-17  9:01   ` Ard Biesheuvel
2020-06-19 16:45 ` [tip: efi/urgent] efi: " tip-bot2 for Peter Jones

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