Based on measurements the EFI functions get_variable / get_next_variable take up to 2us. The functions get_time, set_time take around 10ms. Those 10ms are too much. Even one ms would be too much. The funny part is that EFI is invoked with enabled interrupts. According to my tracing I see the interrupt almost 10ms later which indicates that EFI is disabling interrupts while doing its thing. This was observed on "EFI v2.60 by SoftIron Overdrive 1000". I don't say that every EFI implementation does this but given that it has to access a slow bus like I2C/SPI it is expected. Disable EFI's RTC driver on RT. Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx> --- drivers/rtc/Kconfig | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/drivers/rtc/Kconfig b/drivers/rtc/Kconfig index a2ba5db36145..248d72711650 100644 --- a/drivers/rtc/Kconfig +++ b/drivers/rtc/Kconfig @@ -1087,7 +1087,7 @@ config RTC_DRV_DA9063 config RTC_DRV_EFI tristate "EFI RTC" - depends on EFI && !X86 + depends on EFI && !X86 && !PREEMPT_RT_BASE help If you say yes here you will get support for the EFI Real Time Clock. -- 2.18.0 -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
