Fri, 02 Feb 2007

Lguest Progress

Lguest has seen much progress since my last post. First, James Morris implemented SMP host support, so now lguest is runnable by most people (it still conflicts with CONFIG_X86_PAE, aka HIGHMEM64G, and probably will forever, at least on the guest).

Avi Kivity suggested some simple optimizations (in the area of KVM), which I implemented for lguest, which helped noticeably. He suggested that lguest and kvm share mmu code, which is a good idea except I'm not sure I need all that; for the moment I'm pushing ahead with my own code and I may put some of those ideas into his. In particular, I want the shadow page tables to be susceptible to memory pressure: lguest uses a pool of 1024 for all guests, and kvm uses 256 per guest. Both suck in different ways: lguest is too small, and kvm is bad if you want non-root to run up machines. I'm working on that now.

I implemented bzImage loading for lguest: these kernels are easier to find than a vmlinux, so this is a usability win.

Last but not least, Linux Weekly News published an overview of lguest.

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