Peter Teoh wrote:
Hrm... well, the kernel has the ability since 2.6.20 (although its in testing AFAIK) to relocate itself on a crash. Reference:Sorry if this is a a crazy idea.....just be forewarned.... First, I would like to make a reference to VMWare's snapshot (name not important, emphasize the idea) feature - hopefully u are familiar with it. This is a feature whereby u can freeze the entire OS (kernel + userspace application running) and then later reload itself next time, continuing where it left off, without reboot from ground zero. Next, can I ask, is such a feature useful in Linux? Ie, able to restart the kernel + userspace application from where u left off, the last time round. Not JUST the normal suspend/resume feature, but more important able to CHOOSE among the different available images for u to resume on. Eg, u want to freeze the current 2.6.25-rc6 kernel, save it, and then restore back the 2.6.23-rc5 image, work on it, save it, and then restore the previous image again. All done without virtualization as in the VMWare sense - which really is CPU intensive and slow things down a lot. Now we can directly execute each OS kernel image on the CPU, and since saving and restoring is quite fast (eg, zipping up the entire physical memory before saving into permanent storage) - I supposed this will be much faster than the normal initialization/fsck work done normally....or did I missed out anything? Essentially, to reiterate the key idea: able to snapshot the current kernel+userspace permanent.....restore from another snapshot....and then switch back again if needed etc.....will the implementation be difficult...if not impossible???? Relocatable kernel support for x86This feature (enabled with CONFIG_RELOCATABLE) isn't very noticeable for end-users but it's quite interesting from a kernel POV. Until now, it was a requirement that a i386 kernel was loaded at a fixed memory address in order to work, loading it in a different place wouldn't work. This feature allows to compile a kernel that can be loaded at different 4K-aligned addresses, but always below 1 GB, with no runtime overhead. Kdump users (a feature introduced in 2.6.13 that triggers kexec in a kernel crash in order to boot a kernel that has been previously loaded at an 'empty' address, then runs that kernel, saves the memory where the crashed kernel was placed, dumps it in a file and continues booting the system) will benefit from this because until now the "rescue kernel" needed to be compiled with different configuration options in order to make it bootable at a different address. With a relocatable kernel, the same kernel can be booted at different addresses. (commit 1, 2, 3, 4)Maybe you load up another kernel to handle the snapshot, and then hand the system back to it afterwards? What do you think? |
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