On Tuesday, 17 July 2007 09:34, david@xxxxxxx wrote: > On Tue, 17 Jul 2007, Joseph Fannin wrote: > > > On Mon, Jul 16, 2007 at 11:42:08PM -0700, david@xxxxxxx 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. There's no such requirement, it's just been easier to implement. Greetings, Rafael -- "Premature optimization is the root of all evil." - Donald Knuth _______________________________________________ linux-pm mailing list linux-pm@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/linux-pm
