Re: Back to the future.

From: David Lang
Date: Sat Apr 28 2007 - 15:19:02 EST

On Sat, 28 Apr 2007, Rafael J. Wysocki wrote:
On Friday, 27 April 2007 12:12, Pekka J Enberg wrote:
The problem with writing in the kernel is obvious: we need to add new code
to the kernel for compression, encryption, and userspace interaction
(graphical progress bar) that are important for user experience.

Yes, and that's why we wanted to introduce the userland part. The problem
with this approach, as it's turned out, is that the userland part must be a
very specialized piece of software, really careful of what it's doing, mainly
because of the inability to checkpoint filesystems. If we could checkpoint
filesystems and were able to unfreeze the user space after creating the
snapshot without the risk of corrupting filesystems in the restore phase,
the userland part could be much simpler (even as simple as Linus suggested).

this sounds like a really good argument for having a useable userspace running. we already have the LVM snapshot code in the kernel, so we have the pieces available to protect the filesystems, we just need to figure out how to put them togeather. (the simpliest way would be to make a new suspend package that required the user to use LVM so that snapshots are available, but this is also the most disruptive approach)

David Lang
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