From 119e9db233ad0f4cbd4cfb9f9385a7bca378b37d Mon Sep 17 00:00:00 2001 From: Zeng Chi Date: Mon, 21 Sep 2026 18:24:42 +0800 Subject: KVM: Don't pre-reserve xarray entries when storing empty/NULL attributes Skip the xarray reservation loop when clearing all memory attributes, as storing NULL only erases the entry and never needs to allocate, so no reservation (and no cleanup of a failed one) is required in that case. Suggested-by: Sean Christopherson Cc: David Ballesteros Signed-off-by: Zeng Chi Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com [sean: split to separate patch] Signed-off-by: Sean Christopherson --- Documentation/ABI/testing/rtc-cdev | 50 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 50 insertions(+) create mode 100644 Documentation/ABI/testing/rtc-cdev (limited to 'Documentation/ABI/testing/rtc-cdev') diff --git a/Documentation/ABI/testing/rtc-cdev b/Documentation/ABI/testing/rtc-cdev new file mode 100644 index 000000000..cec099a27 --- /dev/null +++ b/Documentation/ABI/testing/rtc-cdev @@ -0,0 +1,50 @@ +What: /dev/rtcX +Date: April 2005 +KernelVersion: 2.6.12 +Contact: linux-rtc@vger.kernel.org +Description: + The ioctl interface to drivers for real-time clocks (RTCs). + Following actions are supported: + + * RTC_RD_TIME, RTC_SET_TIME: Read or set the RTC time. Time + format is a Gregorian calendar date and 24 hour wall clock + time. + + * RTC_AIE_ON, RTC_AIE_OFF: Enable or disable the alarm interrupt + for RTCs that support alarms + + * RTC_ALM_READ, RTC_ALM_SET: Read or set the alarm time for + RTCs that support alarms. Can be set up to 24 hours in the + future. Requires a separate RTC_AIE_ON call to enable the + alarm interrupt. (Prefer to use RTC_WKALM_*) + + * RTC_WKALM_RD, RTC_WKALM_SET: For RTCs that support a more + powerful interface, which can issue alarms beyond 24 hours and + enable IRQs in the same request. + + * RTC_PIE_ON, RTC_PIE_OFF: Enable or disable the periodic + interrupt for RTCs that support periodic interrupts. + + * RTC_UIE_ON, RTC_UIE_OFF: Enable or disable the update + interrupt for RTCs that support it. + + * RTC_IRQP_READ, RTC_IRQP_SET: Read or set the frequency for + periodic interrupts for RTCs that support periodic interrupts. + Requires a separate RTC_PIE_ON call to enable the periodic + interrupts. + + * RTC_VL_READ: Read the voltage inputs status of the RTC when + supported. The value is a bit field of RTC_VL_*, giving the + status of the main and backup voltages. + + * RTC_VL_CLEAR: Clear the voltage status of the RTC. Some RTCs + need user interaction when the backup power provider is + replaced or charged to be able to clear the status. + + The ioctl() calls supported by the older /dev/rtc interface are + also supported by the newer RTC class framework. However, + because the chips and systems are not standardized, some PC/AT + functionality might not be provided. And in the same way, some + newer features -- including those enabled by ACPI -- are exposed + by the RTC class framework, but can't be supported by the older + driver. -- cgit v1.3.1