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
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