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Re: [Xen-devel] mini-guest io emulation
As Ian mentioned some work needs to be done to make mini-os work on 64 bit platform but the current 32 bit version of mini-os already has:
- simple scheduler (RR like)- memory allocator (buddy allocator, and ported xmalloc build on top of buddy)
- xenbus implementationI've implemented all of it last year. Obviously if we start using it for I/O emulation it will have to be tested more extensively, but it seemed to work just when I used it for my trusted domain builder.
As Aravindh mentioned it his email, we've recently added 64-bit page table builder, which means that the memory allocator should now work on 64bit platform as well.
There are still a few things on TODO list we've created with Aravindh but I think it should be much easier to resolve those then strip Linux down. And I do agree with Jacob, mini-os could be useful for many other things then just I/O emulation.
For the "mini guest", I think it could be much easier if we substantially strip down xenlinux rather than adding (eventually) a lot of stuff to the current mini-os, mainly because we need probably a multi-threaded run-time environment, scheduler, memory allocator, event handling, drivers such as xenbus/netfront/blkfront, etc. At least, I think we can use xenlinux as the development platform. For example, implement the qemu-dm as a driver adding the infrastructure required (e.g. small in-kernel glibc).It seems to me the main reason we needs threads and scheduling is to interact with Xenstore. A page allocator can't be that hard to implement. I wonder if the Xenstore API could be simplified in a way that does not require threading, thus making the job of implementing drivers in a min-os a bit simpler? My feeling is that even a stripped down Linux would take some work to maintain, at least if we wish to remove the need for hotplug scripts for driver backends and the like from the miniLinux. I have little interest in hvm guests, but having a functional mini-os with an extensible, perhaps oskit- or TinyOS-like, structure would be a huge win in a number of other situations as well. If I can I would like to help. If the mini-os ever gets functional, I suppose it would help to include it in the regression tests, to prevent the bit-rot it is currently suffering from. Jacob _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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