Markus Armbruster <arm...@redhat.com> writes: > Avi Kivity <a...@redhat.com> writes: > >> On 11/29/2011 09:03 AM, Jordan Justen wrote: >>> On Mon, Nov 28, 2011 at 02:28, Avi Kivity <a...@redhat.com> wrote: >>> > On 11/28/2011 04:26 AM, Jordan Justen wrote: >>> >> Enable flash emulation in a PC system using pflash_cfi01. >>> > >>> > The new memory layout should be made conditional on the machine type (-M >>> > pc-1.1 or later) to allow migration from/to pc-1.0 and earlier. >>> > >>> > Memory layout in this context are the names of memory ranges given to >>> > memory_region_init_ram(), sizes, and locations. Also, the flash >>> > interface should not be there for older machines. >>> >>> Is this the right way to go about it? >>> 1. Create a new pc-sysfw qdev >>> 2. Use a flash property in pc_piix.c to selectively enable the flash >>> >>> Or, is there an easier or better way to say pc > pc-1.0? >> >> No idea, copying some qdev people. >> >>> How do I enable "migration from/to pc-1.0 and earlier"? It seems like >>> some code will need to shuttle the data (rom <=> pflash). Can you >>> point me an an example? >> >> It should be completely transparent, so long as you instantiate a ROM >> for <= pc-1.0 (say based on a property) and flash for >= pc-1.1. >> >> One way to verify is to to 'info qdev' and 'info mtree' with qemu-1.0 >> and qemu-1.1 -M pc-1.0, and see that you get the same results. > > Gerd created the compatibility machinery (commit b6b61144), and I'm not > really familiar with it. But I can give it a try. > > Our tool to configure devices is qdev properties. > > The device defines property default values. The board can override > them, with QEMUMachine member compat_props.
If you need more than just configuring a device differently, you probably need to hack the board init method. Check out commit 0ec329da for an example. Works roughly like this: * Add suitable parameter to pc_init1() * Change pc_init_pci() to pass the "new behavior on" argument. * Define pc_init_pci_no_kvmclock() like pc_init_pci(), except pass the "new behavior off" argument. Change old boards to use it. [...]
