Messages in this thread | | | Date | Tue, 17 Jul 2007 00:34:16 -0700 (PDT) | From | david@lang ... | Subject | Re: Hibernating To Swap Considered Harmful |
| |
On Tue, 17 Jul 2007, Joseph Fannin wrote:
> On Mon, Jul 16, 2007 at 11:42:08PM -0700, david@lang.hm wrote: >> On Tue, 17 Jul 2007, Joseph Fannin wrote: > >>> root is free to "dd if=/dev/random of=/dev/mem". Root owned >>> daemons which do bad things are bugs. >> >> in this case it would be more like >> >> dd if=/block0 of=/dev/sda1 count=1 bs=4096 skip=5000 >> dd if=/block1 of=/dev/sda1 count=1 bs=4096 skip=5050 >> dd if=/block2 of=/dev/sda1 count=1 bs=4096 skip=5400 >> etc >> >> to write the blocks to the raw parition in the right place > > What I meant by that was that root is allowed to shoot himself in the > foot. Nothing stops root from opening a swap/hibernate file, which > would put it in cache, and cause it to be inconsistant if a > hibernation image was written to it behind the kernel's back. > > That would be a very stupid thing to do, however. There's no reason > to open that file, unless you know *exactly* what you are doing, in > which case the onus is on you to get it right. > > But you have a point. The swap file could be very fragmented. It > might often be so, even. > > Still, is this better than exporting the kernel's swap internals > (which has never been a public interface before)? > > Does it make the interface that writing hibernation images to swap > imposes any better? > > Even if hibernation files are no less complicated to support than > hibernating to swap files (which isn't a forgone conclusion) , there > are plenty of reasons writing hibernation images to swap doesn't make > sense. > > >>> Again, supporting swap files (*which is not optional*) requires the >>> very same support. >> >> in the kexec model why would the second kernel care about swap files at >> all? (unles it chooses to write to them, in which case it is exactly the >> same support, but unless it writes to them it doesn't need to care) > > My point is that no extra work is required to write hibernation images > to dedicated files than to write hibernation images to swap files. > > If swap files are to be supported, then, there's no technical reason > not to support dedicated hibernation files. Dedicated hibernation > files are better, and there's no reason not to implement them.
I agree with your point, but the reverse is not true, the ability to write to a dedicated hibernation file does not produce the capacity to write to a swap file, and I do question the 'requirement' to write the hibernation image to the swap file.
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/
| |