Messages in this thread | | | Date | Thu, 25 Nov 2004 19:53:04 +0100 | From | Pavel Machek <> | Subject | Re: Suspend2 merge: 1/51: Device trees |
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Hi!
> This patch allows the device tree to be split up into multiple trees. I > don't really expect it to be merged, but it is an important part of > suspend at the moment, and I certainly want to see something like it > that will allow us to suspend some parts of the device tree and not > others. Suspend2 uses it to keep alive the hard drive (or equivalent) > that we're writing the image to while suspending other devices, thus > improving the consistency of the image written. > > I remember from last time this was posted that someone commented on > exporting the default device tree; I haven't changed that yet.
Q: I do not understand why you have such strong objections to idea of selective suspend.
A: Do selective suspend during runtime power managment, that's okay. But its useless for suspend-to-disk. (And I do not see how you could use it for suspend-to-ram, I hope you do not want that).
Lets see, so you suggest to
* SUSPEND all but swap device and parents * Snapshot * Write image to disk * SUSPEND swap device and parents * Powerdown
Oh no, that does not work, if swap device or its parents uses DMA, you've corrupted data. You'd have to do
* SUSPEND all but swap device and parents * FREEZE swap device and parents * Snapshot * UNFREEZE swap device and parents * Write * SUSPEND swap device and parents
Which means that you still need that FREEZE state, and you get more complicated code. (And I have not yet introduce details like system devices).
Pavel -- People were complaining that M$ turns users into beta-testers... ...jr ghea gurz vagb qrirybcref, naq gurl frrz gb yvxr vg gung jnl! - 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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