Re: [PATCH v1 17/32] liveupdate: luo_sysfs: add sysfs state monitoring
From: Randy Dunlap <rdunlap@infradead.org>
Date: 2025-06-26 00:29:57
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linux-doc, linux-fsdevel, linux-mm, lkml
Hi, On 6/25/25 4:18 PM, Pasha Tatashin wrote:
quoted hunk ↗ jump to hunk
diff --git a/Documentation/ABI/testing/sysfs-kernel-liveupdate b/Documentation/ABI/testing/sysfs-kernel-liveupdate new file mode 100644 index 000000000000..4cd4a4fe2f93 --- /dev/null +++ b/Documentation/ABI/testing/sysfs-kernel-liveupdate@@ -0,0 +1,51 @@ +What: /sys/kernel/liveupdate/ +Date: May 2025 +KernelVersion: 6.16.0 +Contact: pasha.tatashin@soleen.com +Description: Directory containing interfaces to query the live + update orchestrator. Live update is the ability to reboot the + host kernel (e.g., via kexec, without a full power cycle) while + keeping specifically designated devices operational ("alive") + across the transition. After the new kernel boots, these devices + can be re-attached to their original workloads (e.g., virtual + machines) with their state preserved. This is particularly + useful, for example, for quick hypervisor updates without + terminating running virtual machines. + + +What: /sys/kernel/liveupdate/state +Date: May 2025 +KernelVersion: 6.16.0 +Contact: pasha.tatashin@soleen.com +Description: Read-only file that displays the current state of the live + update orchestrator as a string. Possible values are: + + "normal": No live update operation is in progress. This is + the default operational state.
Just an opinion, but the ':'s after each possible value aren't needed
and just add noise.
You could just drop the ':'s -- or you could make a table here, like
Documentation/ABI/testing/sysfs-hypervisor-xen does, by adding
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+ "prepared": The live update preparation phase has completed + successfully (e.g., triggered via the + /dev/liveupdate event). Kernel subsystems have + been notified via the %LIVEUPDATE_PREPARE + event/callback and should have initiated state + saving. User workloads (e.g., VMs) are generally + still running, but some operations (like device + unbinding or new DMA mappings) might be + restricted. The system is ready for the reboot + trigger. + + "frozen": The final reboot notification has been sent + (e.g., triggered via the 'reboot()' syscall), + corresponding to the %LIVEUPDATE_REBOOT kernel + event. Subsystems have had their final chance to + save state. User workloads must be suspended. + The system is about to execute the reboot into + the new kernel (imminent kexec). This state + corresponds to the "blackout window". + + "updated": The system has successfully rebooted into the + new kernel via live update. Restoration of + preserved resources can now occur (typically via + ioctl commands). The system is awaiting the + final 'finish' signal after user space completes + restoration tasks.
and
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Or just disagree or ignore. :)
--
~Randy