On Tue, 17 Jul 2007, Alan Stern wrote:
On Tue, 17 Jul 2007 david@xxxxxxx wrote:
But what about the freezer? The original reason for using kexec was to
avoid the need for the freezer. With no freezer, while the original
kernel is busy powering down its devices, user tasks will be free to
carry out I/O -- which will make the memory snapshot inconsistent with
the on-disk data structures.
no, user tasks just don't get scheduled during shutdown.
But a user task may be holding a lock which is needed for putting some
device into low-power mode. It can't release that lock if it doesn't
get scheduled.
then you can't suspend that box. if you schedule it, it could get another
lock (or another process gets another lock)
if you can't power down or put hardware into low-power mode without the
approval of userspace, you are in serious trouble.
David Lang
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