"Major Linux distributors have been shipping ACPI in Linux for several years, yet mis-perceptions about ACPI persist in the Linux community. This paper addresses the most common myths about ACPI in Linux [.pdf]." In addition, there are proposals to utilise kexec-based hibernation in Linux.
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Member since:2005-07-08
You're correct.
Any code running on bare metal in kernel mode has the potential to barf all over memory until it barfs all over itself. Only hardware virtualization can contain the damage. But this is an unlikely scenario. The most common cause of data corruption is that the code that's supposed to be playing with the data does something wrong. The odds of the capture kernel getting trashed are slim because nothing in the production kernel is supposed to be playing with its data.
So, there is no design that guarantees that we will always be able to dump a crashed host kernel. But we can dramatically increase our chances by using a separate capture kernel, and nothing in a virtual machine can negatively impact the hypervisor's ability to dump it. The hypervisor could crash on its own, of course, but not because the virtual machine crashed.
Member since:
2005-09-14
Out of curiosity, if the capture kernel were preloaded, wouldn't it be just as vulnerable to getting trashed as anything else in mem? Conversely, if it's not preloaded, how do you ensure that whatever block of code is responsible for loading the capture kernel isn't itself trashed? Does it require hypervisor support to be reliable?