1 files changed, 41 insertions, 0 deletions
diff --git a/debian/patches-rt/efi-Disable-runtime-services-on-RT.patch b/debian/patches-rt/efi-Disable-runtime-services-on-RT.patch
new file mode 100644
index 000000000..c4a4099f6
--- /dev/null
+++ b/debian/patches-rt/efi-Disable-runtime-services-on-RT.patch
@@ -0,0 +1,41 @@
+From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+Date: Thu, 26 Jul 2018 15:03:16 +0200
+Subject: [PATCH] efi: Disable runtime services on RT
+Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.15/older/patches-5.15.3-rt21.tar.xz
+
+Based on measurements the EFI functions get_variable /
+get_next_variable take up to 2us which looks okay.
+The functions get_time, set_time take around 10ms. These 10ms are too
+much. Even one ms would be too much.
+Ard mentioned that SetVariable might even trigger larger latencies if
+the firmware will erase flash blocks on NOR.
+
+The time-functions are used by efi-rtc and can be triggered during
+run-time (either via explicit read/write or ntp sync).
+
+The variable write could be used by pstore.
+These functions can be disabled without much of a loss. The poweroff /
+reboot hooks may be provided by PSCI.
+
+Disable EFI's runtime wrappers on PREEMPT_RT.
+
+This was observed on "EFI v2.60 by SoftIron Overdrive 1000".
+
+Acked-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
+Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+Link: https://lkml.kernel.org/r/20210924134919.1913476-2-bigeasy@linutronix.de
+---
+ drivers/firmware/efi/efi.c |    2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+--- a/drivers/firmware/efi/efi.c
++++ b/drivers/firmware/efi/efi.c
+@@ -66,7 +66,7 @@ struct mm_struct efi_mm = {
+ 
+ struct workqueue_struct *efi_rts_wq;
+ 
+-static bool disable_runtime;
++static bool disable_runtime = IS_ENABLED(CONFIG_PREEMPT_RT);
+ static int __init setup_noefi(char *arg)
+ {
+ 	disable_runtime = true;