On Mon, Aug 25, 2008 at 10:06:58AM +0800, Max Zhen wrote: > > My question is whether it is possible to use mdb on the control domain to > > debug a guest domain and do things like set a breakpoint on the domain > > being debugged (as 1 example of what should be possible if I could do > > this)? This could be a stupid question but I thought it would be a cool > > thing to try out. If there is some reason why it is not possible to do > > this, I'd appreciate if anyone could explain why to me. > > > I don't think you can debug a running domain from dom0 using mdb at this > point. > AFAIK, dom0 cannot freely access memory pages which belongs to a domU. > Explicit access permission needs to be granted by the domU before dom0 > can access the page (map it into dom0's address space and write to it, > say, set a break point).
Actually, this isn't true: if it was, then virsh dump wouldn't be able to work. dom0 can map all of a guest's memory. Padraig: you're right it would be a cool thing to do, and I've wanted this for quite a while. There's actually not that many changes needed to mdb for this to happen. The code that understands how to bootstrap mdb into a Xen domain already exists (mdb_kb). The main missing part is an implementation of vread/write that knows to use the hypercall that maps in domU memory. regards john _______________________________________________ xen-discuss mailing list [email protected]
