Hi,
We recently observed that the LTP rtc01 RTC alarm test fails on intel
based VM's. This seems to be observed after the commit
6492fed7d8c95f53b0b804ef541324d924d95d41 - ("rtc: rtc-cmos: Do not check
ACPI_FADT_LOW_POWER_S0")
I noticed that the use_acpi_alarm was set to "N" before the commit, now
it is set as "Y"
# cat /sys/module/rtc_cmos/parameters/use_acpi_alarm
Y
#./runltp -d /tmpdir -s rtc01
<<<test_output>>>
incrementing stop
rtc01 0 TINFO : RTC READ TEST:
rtc01 1 TPASS : RTC READ TEST Passed
rtc01 0 TINFO : Current RTC date/time is 3-3-2025, 21:02:20.
rtc01 0 TINFO : RTC ALARM TEST :
rtc01 0 TINFO : Alarm time set to 21:02:25.
rtc01 0 TINFO : Waiting 5 seconds for the alarm...
rtc01 2 TFAIL : rtc01.c:151: Timed out waiting for the alarm
rtc01 0 TINFO : RTC UPDATE INTERRUPTS TEST :
rtc01 0 TINFO : Waiting for 5 update interrupts...
rtc01 3 TFAIL : rtc01.c:208: Timed out waiting for the update
interrupt
rtc01 0 TINFO : RTC Tests Done!
I believe that the hypervisor may not fully support ACPI or may
implement it differently than physical hardware. ACPI wake-up events may
not be properly supported or may be emulated differently in the VM,
causing alarms to not trigger correctly or time out.
On AMD all instances the use_acpi_alarm is set to "N" so no issue seen.
On intel Bare metal instances the use_acpi_alarm is set to "Y" but no
issue seen.
But, on intel VM's the use_acpi_alarm is set to "Y" and the issue is seen.
I even check with
# acpidump > acpidump.txt
# grep "FADT" acpidump.txt
no output from above saying that ACPI_FADT_LOW_POWER_S0 is not set.
Is it possible to know we can address this issue? Should we make changes
in the LTP test itself? or in the kernel?
