Messages in this thread |  | | | Date | Fri, 20 Jul 2007 13:31:04 -0700 (PDT) | | From | david@lang ... | | Subject | Re: [linux-pm] Re: Hibernation considerations |
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On Fri, 20 Jul 2007, Alan Stern wrote:
> On Fri, 20 Jul 2007, Milton Miller wrote: > >>> We can't do this unless we have frozen tasks (this way, or another) >>> before >>> carrying out the entire operation. >> >> What can't we do? We've already worked with the drivers to quesce the >> hardware and put any information to resume the device in ram. Now we >> ask them to put their device in low power mode so we can go to sleep. >> Even if we schedule, the only thing userspace could touch is memory. > > Userspace can submit I/O requests. Someone will have to audit every > driver to make sure that such I/O requests don't cause a quiesced > device to become active. If the device is active, it will make the > memory snapshot inconsistent with the on-device data.
assuming this is the suspend-from-ram after a kexec back from the write-to-disk kernel I don't think you are correct.
when doing a suspend-to-ram you get to a point where you just don't use any userspace. from that point on you are just walking the device tree putting things into low-power mode. This is the point where we are talking about jumping to.
david Lang - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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