Messages in this thread | | | Date | Fri, 14 Feb 2003 14:00:31 -0600 | From | Corey Minyard <> | Subject | Re: Kexec, DMA, and SMP |
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Werner Almesberger wrote:
|Zwane Mwaikambo wrote: | |>I don't think suspending devices is safe at that stage since removing |>devices and walking lists and freeing memory and disabling devices and... |>kicks up quite a storm. | | |If you *really* don't want to stop devices, you can use the |"reserved, non-DMA memory" approach, kexec the kernel that |records the crash dump, and then do a system-wide reset, or |such. | |But if you don't have that - possibly considerable - amount |of memory to spare, you don't have much of a choice than to |stop devices. Of course, crash dumps don't need a neat and |clean shutdown, so you can avoid all the kfrees, and such. | |(So adding a special mode to the power management code may |be too much overhead. Besides, sometimes, you can just pull |a reset line, and don't have to do anything even remotely |related to power management.)
True, I didn't mean the high-level power management code directly. But the PCI API defines a suspend operation that could take a special mode for this. Or maybe a new field in the PCI structure (and equivalent for other things, if there are any). But the suspend and resume operations should at least give a good idea where its needed and how to use it.
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