How to detect rebooting into kexec'd kernel

[Philip Prindeville]

How do you tell you’re in the new kernel?

There doesn’t seem to be anything in /sys/kernel/ that indicates this.

I could parse /proc/cmdline for the absence of “crashkernel=“ for instance, but there are obvious pitfalls to that.

You’d think there would be a way for the kexec’d kernel to maintain some sort of marker making it obvious that this is the kexec’d kernel (especially if your system kernel and your crash kernel are the same, and only the cmdline arguments change).

Thanks,

-Philip

[Baoquan He]

For kdump kernel, check /proc/vmcore
kexec kernel, no way.

Post by Philip Prindeville
How do you tell you’re in the new kernel?
There doesn’t seem to be anything in /sys/kernel/ that indicates this.
I could parse /proc/cmdline for the absence of “crashkernel=“ for instance, but there are obvious pitfalls to that.
You’d think there would be a way for the kexec’d kernel to maintain some sort of marker making it obvious that this is the kexec’d kernel (especially if your system kernel and your crash kernel are the same, and only the cmdline arguments change).
Thanks,
-Philip
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