On 02/10/16 02:05, Tarl Neustaedter wrote:
On 2016-Oct-1 20:47 , G 3 wrote:
Actually the Mac OS gets all its information from the VGA driver. It would be the VGA driver that would read the list in OpenBIOS. Currently the VGA driver needs the list to an array of integers.
O.k. - misunderstood. The new VGA driver is a MacOS driver, not a OpenBIOS driver. So we aren't booting standard MacOS, but a modified version.
The traditional way information is passed (for IEEE1275 in Sun/Oracle style) from the outside world into drivers/operating systems is with properties in either /chosen or /options. Properties in /options mimic NVRAM variables, looking like they might have been set by the previous iteration of an operating system - that's probably not ideal, it might appear that the client OS could set them, which wouldn't be the case. Properties in /chosen are places where firmware stores anything it determines at startup for use by later clients.
I would suggest in this case that /chosen would be your better location than a device node.
At the moment the screen width/height/depth can be found in 2 places: i) via Bochs VBE extensions and ii) the QEMU fw_cfg interface.
During PROM startup the latter is used to construct the width, height and depth properties for the QEMU,VGA device node which is currently how this is exposed to the guest.
ATB,
Mark.