On Thu, Feb 09, 2017 at 04:10:43PM +0100, Andrea Bolognani wrote: > On Thu, 2017-02-09 at 13:28 +0100, Andrew Jones wrote: > > > Please keep in mind that I want to be able > > > to use the very same paragraph both for q35 and mach-virt. > > > > I'm not sure having the exact same paragraph is a reasonable > > goal. > > If not the exact same, there is no reason for it not to > be at least 90% shareable IMHO. > > > Does q35 have platform devices like mach-virt? > > I don't know. And I'm not sure we need to talk about them > or their aarch64 counterparts at all in the sample > configuration file, because AFAIK with the exception of the > GIC version they are not user configurable, or at the very > least not something the user will actively want to > configure (correct me if I'm wrong).
I'm OK with not mentioning them "too much" in this file. I agree with Peter though that to be more accurate we shouldn't state that '-nodefaults' results in a machine with nothing. Therefore, some wording that states -nodefaults ensures no non-builtin peripherals are automatically added, but builtin peripherals, such as the PL011, will remain, seems like a good idea. > > > The > > devices we get on a 'qemu -nodefaults -machine virt' instance > > are MMIO driven devices on the board, rather than devices > > hung off the pcie host bridge. > > We want people to use PCIe instead of MMIO, though, so > again why should we even mention those? We want to use virtio-pci devices, as opposed to virtio-mmio devices, which means using the PCIe ports you add vs. the virtio-mmio transports. That doesn't mean we don't still want to use the MMIO devices builtin to the board though, the PL011 (UART) being a prime example. > > It's just a sample configuration file we're talking about, > not a complete reference of the aarch64 architecture, so > it's entirely okay to skimp on details that don't directly > impact most users and be opinionated. I agree with being skimpy, but we don't want to cross the line into misleading. > > > Perhaps we can list the uart as an example; I don't suppose > > it'll ever be removed. If we use wording such as "such as", > > then it allows expansion to the board without a commitment to > > update the list. > > > > BTW, when I stated "-nodefaults provides us a base mach-virt > > board with no peripherals.", I meant no _additional_ > > peripherals plugged into the board's virtio-mmio transports, > > nor hung off the host bridge. Is there a word for those? > > Maybe just non-builtin peripherals? > > Please propose the alternative wording you'd like to see > so we can discuss it :) I guess I did above with "... -nodefaults ensures no non-builtin peripherals are automatically added, but builtin peripherals, such as the PL011, will remain..." Thanks, drew
