On 11/11/2010 02:56 AM, Huang Ying wrote:
On Thu, 2010-11-11 at 00:49 +0800, Anthony Liguori wrote: > On 11/10/2010 02:34 AM, Avi Kivity wrote: > >> Why the gpa -> hva mapping is not > >> consistent for RAM if -mempath is not used? > > > > Video RAM in the range a0000-bffff and PCI mapped RAM can change gpas > > (while remaining in the same hva). > > > > Even for ordinary RAM, which doesn't normally change gpa/hva, I'm not > > sure we want to guarantee that it won't. > > We can't universally either. Memory hot remove potentially breaks the > mapping and some non-x86 architectures (like ARM) can alias RAM via a > guest triggered mechanism. Thanks for clarification. Now I think we have two options. 1) Clearly mark gpa2hva (pfa2hva now, should renamed to gpa2hva) as a testing only interface, and should be used only on restricted environment (normal memory, without hot-remove, maybe only on x86). 2) Find some way to lock the gpa -> hva mapping during operating. Such as gpa2hva_begin and gpa2hva_end and lock the mapping in between. I think 2) may be possible. But if there are no other users, why do that for a test case? So I think 1) may be the better option.
3) Move the poisoning code into qemu, so the command becomes posison-address <addr> (though physical addresses aren't stable either) 4) Use -mempath on /dev/shm and poison a page in the backing file (if poisoning works on tmpfs) -- error compiling committee.c: too many arguments to function -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
