Hi Grant, The patch series for dts driven machine creation we (myself and Edgar) use that you are referring to was rejected a few months ago on the grounds that it conflicted with QOM:
http://lists.gnu.org/archive/html/qemu-devel/2011-08/msg02953.html I am maintaining it our of tree, although I have not fast forwarded that branch for a while, so I cant recreate that series quickly. But now that QOM is immenent, can we get another review on the original series, and comments on what needs to happen to make this play nice with QOM? There is nothing in this series that is target specific, Adaption for arm should be fairly trivial. Peter On Fri, Jan 27, 2012 at 10:34:01PM +0000, Paul Brook wrote: > > > If compiled with CONFIG_FDT, allow user to specify a device tree file > using > > > the -dtb argument. If the machine supports it then the dtb will be > loaded > > > into memory and passed to the kernel on boot. > > > > Adding annother machine feels wrong. Why does the board specific code > need to > > know about this at all? You already going it via a global variable, so > can't > > this be entirely contained within arm_boot.c? > > Mostly because the infrastructure isn't yet in place to pass the .dtb file > through to the arm_boot code (or maybe it is; what is the best way to pass > command line data through to the arm_boot.c code (or similar for other > architectures)? > > > If the board file is involved, why is it asking the user? > > There is a lot of configuration in the .dts file that the QEMU user may > want > to manipulate; particularly when using QEMU for testing embedded platforms. > The direction I want to go is to select the machine model based on the top > level DT compatible property (making -M optional), and then also allow a > lot > of the machine layout to be driven by DT data. ie. populate emulated > devices > from DT data. > > I believe this is how Edgar is using the microblaze model, but I don't > think those patches have been upstreamed yet. I hope that microblaze, > ARM and powerpc can all use the same model here. > > > > > > + versatile_init(ram_size, > > > + boot_device, > > > + kernel_filename, kernel_cmdline, > > > + initrd_filename, cpu_model, 0xffffffff); > > > > This only works because we're currently too dumb to emulate the > differences > > between the two board variants. > > Yeah, this is a hack so I could play with forcing the machine id. > I'll remove it. > > > What we probably want to be doing is shipping/constructing device trees > for > > the boards we implement, with an option to turn this on/off. Requiring > a user > > to invent their own seems deeply sub-optimal given we know exactly what > > hardware we're emulating. A user that needs to provide their own FDT > seems > > like a fairly rare corner case. > > I disagree. QEMU may want to ship stock .dts files, but it will > absolutely be a common use case for embedded developers to pass in > their own .dtb file. > > > This gets slightly more interesting when you have custom machine variants > > (i.e. once we fix the object model, and have proper dynamic machine > > construction). Even then I'd expect the FDT to be derived > from/specificed by > > the machine description, not a separate option. > > I started with going down that route, but switched to this model after > playing with it and noticing that it doesn't seem to fit as well for > embedded development as providing a .dtb file and having QEMU > construct a machine that matches the data. > > g. > >
