Linux Virtualization with Lguest

摘自Linux Virtualization with Lguest，Author：John Quigley

Lguest Launcher

Launcher is an ELF userspace app that launches and monitors guests。

它执行以下任务：

1. maps guest kernel imagine into host’s memory

2.opens /dev/lguest and writes config info about guest

3.hypervisor uses this to initialize and launch guest

4.open procfile used for ongoing control, console I/O,DMA-like I/O via shmem

注意: Physical memory in the Guest is the Host’s virtual memory.

Lguest Hypervisor

The hypervisor is simply a loadablekernel module... cool!

Being able to insert a module and start new guest

provides "low commitment" path to virtualization

Provides the /dev/lguest interface, whereby userspace

launcher controls and communicates with guest

First write tells us memory size, pagetable, entry point,kernel offset

A read will run guest until pending signal (-EINTR), or guest does DMA out to launcher

The Lguest hypervisor is unique in several ways.

Host domain is simply a normal kernel in ring-0

Hypervisor is loaded into top of kernel memory

Hypervisor contains only core facilities:

1domain switching code

2 interrupt handlers

3 few low-level object that need to be virtualized

4 array of structs to maintain info for each guest domain
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