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authorZeng Chi <zengchi@kylinos.cn>2026-09-21 18:24:42 +0800
committerSean Christopherson <seanjc@google.com>2026-09-22 08:36:16 -0700
commit119e9db233ad0f4cbd4cfb9f9385a7bca378b37d (patch)
tree660d50d4139cb750fbde1ae3432452c20726c99d /Documentation/ABI/testing/sysfs-kernel-fadump
downloadlinux-stable-119e9db233ad0f4cbd4cfb9f9385a7bca378b37d.tar.gz
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KVM: Don't pre-reserve xarray entries when storing empty/NULL attributesgrafted
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 <seanjc@google.com> Cc: David Ballesteros <davimaba.v@proton.me> Signed-off-by: Zeng Chi <zengchi@kylinos.cn> Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com [sean: split to separate patch] Signed-off-by: Sean Christopherson <seanjc@google.com>
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+What: /sys/kernel/fadump/*
+Date: Dec 2019
+Contact: linuxppc-dev@lists.ozlabs.org
+Description:
+ The /sys/kernel/fadump/* is a collection of FADump sysfs
+ file provide information about the configuration status
+ of Firmware Assisted Dump (FADump).
+
+What: /sys/kernel/fadump/enabled
+Date: Dec 2019
+Contact: linuxppc-dev@lists.ozlabs.org
+Description: read only
+ Primarily used to identify whether the FADump is enabled in
+ the kernel or not.
+User: Kdump service
+
+What: /sys/kernel/fadump/registered
+Date: Dec 2019
+Contact: linuxppc-dev@lists.ozlabs.org
+Description: read/write
+ Helps to control the dump collect feature from userspace.
+ Setting 1 to this file enables the system to collect the
+ dump and 0 to disable it.
+User: Kdump service
+
+What: /sys/kernel/fadump/release_mem
+Date: Dec 2019
+Contact: linuxppc-dev@lists.ozlabs.org
+Description: write only
+ This is a special sysfs file and only available when
+ the system is booted to capture the vmcore using FADump.
+ It is used to release the memory reserved by FADump to
+ save the crash dump.
+
+What: /sys/kernel/fadump/mem_reserved
+Date: Dec 2019
+Contact: linuxppc-dev@lists.ozlabs.org
+Description: read only
+ Provide information about the amount of memory reserved by
+ FADump to save the crash dump in bytes.
+
+What: /sys/kernel/fadump/hotplug_ready
+Date: Apr 2024
+Contact: linuxppc-dev@lists.ozlabs.org
+Description: read only
+ Kdump udev rule re-registers fadump on memory add/remove events,
+ primarily to update the elfcorehdr. This sysfs indicates the
+ kdump udev rule that fadump re-registration is not required on
+ memory add/remove events because elfcorehdr is now prepared in
+ the second/fadump kernel.
+User: kexec-tools
+
+What: /sys/kernel/fadump/bootargs_append
+Date: May 2024
+Contact: linuxppc-dev@lists.ozlabs.org
+Description: read/write
+ This is a special sysfs file available to setup additional
+ parameters to be passed to capture kernel. For HASH MMU it
+ is exported only if RMA size higher than 768MB.