On 05/22/2012 08:31 AM, Gleb Natapov wrote: > On Mon, May 21, 2012 at 04:30:41PM -0300, Marcelo Tosatti wrote: >> On Mon, May 21, 2012 at 04:15:50PM +0800, Xiao Guangrong wrote: >> > On 05/21/2012 04:08 PM, Gleb Natapov wrote: >> > >> > > On Mon, May 21, 2012 at 02:45:45PM +0800, Xiao Guangrong wrote: >> > >> If we map a readonly memory space from host to guest and the page is >> > >> not currently mapped in the host, we will get a fault-pfn and async >> > >> is not allowed, then the vm will crash >> > >> >> > > Why would we want to map a readonly memory space from host to guest? >> > > We may want to do it to support memory semantics on read and mmio on >> > > write, but do not right now unless something changed while I was not >> > > looking. >> > >> > >> > Some test cases in kvm-unit-tests and the benchmark i am writing for KVM >> > need map the function on host to guest. >> >> Or ROM. Or read-only mappings of IVSHMEM (which don't exist yet). > True. KVM should ignore writes to such areas, not kill a guest. Is this > how the code works today? > Right now qemu maps ROM as RAM. There is no way to tell kvm that something is ROM (or ROMD). There are two options for that: - mprotect() the ROM, and teach kvm about read-only areas (this patch); but that doesn't work if we have a read-only and a writable alias of the same area - add a flag indicating that an area is ROM or ROMD I prefer the latter, because of the alias issue. -- 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
