Messages in this thread | | | Date | Sat, 14 Jul 2007 00:12:04 -0700 (PDT) | From | david@lang ... | Subject | Re: [PATCH 0/2] Kexec jump: The first step to kexec base hibernation |
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On Fri, 13 Jul 2007, Rafael J. Wysocki wrote:
>> remember release early, release often (with something that functions) >> >>>> fo rthe current stage where we are trying to make things work don't worry >>>> about packaging everything tight with initrd and re-useing partitions or >>>> kernel images. once everything is working reliably then it's time to look >>>> at useing the same kernel for multiple functions, writing to a partition >>>> that's i use for other things, etc >>> >>> I don't agree. You need to think of many limitations in advance, because >>> they need to be taken into consideration in the design. >>> >>> Otherwise we'll end up with something that will need to be bandaided like the >>> freezer. :-) >> >> on the other hand, worrying about all the possible ways to do things can >> paralize you. >> >> the big advantage of the kexec approach is that the new userspace that's >> setup with the new kernel can do _anything_. > > No, it can't. For example, it can't access filesystems mounted by the > hibernated kernel, or they may get corrupted after the restore (if they are > journaling, it can't even read from them).
it's only ext3 that has this bug when mounting a fileystem read-only AFAIK.
> Which reminds me of one more issue, which is that the image-saving kernel > won't be able to use these filesystems either, so its modules and user space > will have to be available from somewhere else (like a RAM disk or dedicated > partition). So things get ugly.
another reason to go ahead and make a dedicated no-module kernel for the hibernate phase ;-)
> Apart from this, the new kernel's user space cannot blindly modify swap space > that might be in use by the hibernated kernel.
with swap space you have two options
1. free it up (to a swap file if needed) and don't worry about it
2. try and ensure that nothing else on the system attempts to use the swap partition until you reboot.
#2 is failure prone, #1 would be more reliable.
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