suspend, kdump, swap, ...

Posted Feb 10, 2006 21:40 UTC (Fri) by utoddl (guest, #1232)
Parent article: Software suspend - again

Just tossing an idea out in ignorance (I don't know much about how the competing suspend models work), but it seems we've got another mechanism we could use beside kdump. We already page data and programs out to swap. Could we not page out everything including the running kernel too (without freeing the RAM of course) so that an early step in rebooting would be to examine swap and see if it looked like it contained a viable "kernel+user space image" and do the Right Thing with it?

Another thought: kdump only requires a private kernel to do the dump because the "real" kernel is presumably injured. Seems that if the kdump technique were used for suspend, wouldn't it be safe to assume the main kernel is okay and let it do the dump? No need for a special dump kernel.

Wish I knew what I was talking about. -- Cheers

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suspend, kdump, swap, ...

Posted Feb 11, 2006 0:40 UTC (Sat) by giraffedata (guest, #1954) [Link]

The challenge of suspend to disk isn't really the task of saving a memory image and restoring it later. The state of the system lives in various places besides main memory that dissolve when the power goes off. For example, an Ethernet adapter has plenty of state in its own memory. Plus, some parts of the system can't tolerate having hours pass in the blink of an eye. So they have to know about the sleep and actively go to sleep and wake up.