On Tue, Mar 06, 2018 at 12:16:08PM +0800, Haozhong Zhang wrote: > On 03/02/18 12:03 +0000, Anthony PERARD wrote: > > On Wed, Feb 28, 2018 at 05:36:59PM +0800, Haozhong Zhang wrote: > > > On 02/27/18 17:22 +0000, Anthony PERARD wrote: > > > > On Thu, Dec 07, 2017 at 06:18:02PM +0800, Haozhong Zhang wrote: > > > > > This is the QEMU part patches that works with the associated Xen > > > > > patches to enable vNVDIMM support for Xen HVM domains. Xen relies on > > > > > QEMU to build guest NFIT and NVDIMM namespace devices, and allocate > > > > > guest address space for vNVDIMM devices. > > > > > > > > I've got other question, and maybe possible improvements. > > > > > > > > When QEMU build the ACPI tables, it also initialize some MemoryRegion, > > > > which use more guest memory. Do you know if those regions are used with > > > > your patch series on Xen? > > > > > > Yes, that's why dm_acpi_size is introduced. > > > > > > > Otherwise, we could try to avoid their > > > > creation with this: > > > > In xenfv_machine_options() > > > > m->rom_file_has_mr = false; > > > > (setting this in xen_hvm_init() would probably be better, but I havn't > > > > try) > > > > > > If my memory is correct, simply setting rom_file_has_mr to false does > > > not work (though I cannot remind the exact reason). I'll have a look > > > as the code to refresh my memory. > > > > I've played a bit with this idea, but without a proper NVDIMM available > > for the guest, so I don't know if it's going to work properly without > > the mr. > > > > To make it work, I had to disable some code in acpi_build_update() that > > make use of the MemoryRegions, as well as an assert in acpi_setup(). > > After those small hacks, I could boot the guest, and I've check that the > > expected ACPI tables where there, and they looked correct to my eyes. > > And least `ndctl list` works and showed the nvdimm (that I have > > configured on QEMU's cmdline). > > > > But I may not have been far enough with my tests, and maybe something > > later relies on the MRs, especially the _DSM method that I don't know if > > it was working properly. > > > > Anyway, that why I proposed the idea, and if we can avoid more > > uncertainty about how much guest memory QEMU is going to use, that would > > be good. > > > > Yes, I also tested some non-trivial _DSM methods and it looks rom > files without memory regions can work with Xen after some > modifications. I'll apply this idea in the next version if no other > issues are found.
Awesome, thanks. -- Anthony PERARD