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-rw-r--r--debian/patches-rt/0192-efi-Disable-runtime-services-on-RT.patch46
1 files changed, 46 insertions, 0 deletions
diff --git a/debian/patches-rt/0192-efi-Disable-runtime-services-on-RT.patch b/debian/patches-rt/0192-efi-Disable-runtime-services-on-RT.patch
new file mode 100644
index 000000000..ed06b5934
--- /dev/null
+++ b/debian/patches-rt/0192-efi-Disable-runtime-services-on-RT.patch
@@ -0,0 +1,46 @@
+From 6c6afc933fea370e5c90a34ed6b622bcc274af5a Mon Sep 17 00:00:00 2001
+From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+Date: Thu, 26 Jul 2018 15:03:16 +0200
+Subject: [PATCH 192/323] efi: Disable runtime services on RT
+Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.10/older/patches-5.10.204-rt100.tar.xz
+
+Based on meassurements the EFI functions get_variable /
+get_next_variable take up to 2us which looks okay.
+The functions get_time, set_time take around 10ms. Those 10ms are too
+much. Even one ms would be too much.
+Ard mentioned that SetVariable might even trigger larger latencies if
+the firware will erase flash blocks on NOR.
+
+The time-functions are used by efi-rtc and can be triggered during
+runtimed (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.
+
+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>
+---
+ drivers/firmware/efi/efi.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
+index 332739f3eded..8d390091203f 100644
+--- 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;
+--
+2.43.0
+