@@ -284,3 +284,18 @@ config EFI_CUSTOM_SSDT_OVERLAYS
See Documentation/admin-guide/acpi/ssdt-overlays.rst for more
information.
+
+config EFI_DISABLE_RUNTIME
+ bool "Disable EFI runtime services support by default"
+ default y if PREEMPT_RT
+ help
+ Allow to disable the EFI runtime services support by default. This can
+ already be achieved by using the efi=noruntime option, but it could be
+ useful to have this default without any kernel command line parameter.
+
+ The EFI runtime services are disabled by default when PREEMPT_RT is
+ enabled, because measurements have shown that some EFI functions calls
+ might take too much time to complete, causing large latencies which are
+ an issue for RT.
+
+ This default can be overridden by using the efi=runtime option.
@@ -66,7 +66,7 @@ struct mm_struct efi_mm = {
struct workqueue_struct *efi_rts_wq;
-static bool disable_runtime = IS_ENABLED(CONFIG_PREEMPT_RT);
+static bool disable_runtime = IS_ENABLED(CONFIG_EFI_DISABLE_RUNTIME);
static int __init setup_noefi(char *arg)
{
disable_runtime = true;
Commit d9f283ae71af ("efi: Disable runtime services on RT") disabled EFI runtime services when the CONFIG_PREEMPT_RT option is enabled. The rationale for the change is that some EFI calls could take too much time, leading to large latencies which are an issue for RT kernels. But a side effect of that commit is that now is not possible anymore to enable the EFI runtime services by default when CONFIG_PREEMPT_RT is set to y, even for platforms that could guarantee bounded time for EFI calls. Instead, let's add a new EFI_DISABLE_RUNTIME boolean Kconfig option, that would be set to n by default but to y if CONFIG_PREEMPT_RT is enabled. That way, the current behaviour is preserved but gives users a mechanism to enable the EFI runtimes services in their kernels if that is required. Reported-by: Alexander Larsson <alexl@redhat.com> Fixes: d9f283ae71af ("efi: Disable runtime services on RT") Signed-off-by: Javier Martinez Canillas <javierm@redhat.com> --- drivers/firmware/efi/Kconfig | 15 +++++++++++++++ drivers/firmware/efi/efi.c | 2 +- 2 files changed, 16 insertions(+), 1 deletion(-)