On Sep 21, 2016, at 5:01 AM, Benjamin Herrenschmidt wrote:
On Tue, 2016-09-20 at 22:54 -0400, G 3 wrote:
You really want to remove the included list of resolutions? I was
thinking about adding a lot more built-in resolutions in another
patch. A built-in list is very convenient.
I mean remove it from the driver and put it in OpenBIOS instead.
Ie. have openbios build the resolution list from the combination of
what you put
in the options node and its own built-in list.
That idea is shared with others. OpenBIOS might be considered easier
to alter than the VGA driver, so this might be best.
As for the options node problem. We need a way to add resolutions
from the command-line for a Mac OS X guest. Using "-prom-env" isn't
an option because of some unknown bug.
Maybe, I can look into it later, but the above would fix it nicely.
Nodes like chose, aliases, openprom are of class IOService. options
is of class IODTNVRAM. It looks like this class has problems. I'm
thinking since Alexander Graf did work in the mac_nvram.c file, he
might know what is wrong. I found another way to access the options
node in Mac OS X. Use this command: ioreg -c IODTNVRAM. It stops at
the options node and prints this error message: "ioreg: error: can't
obtain properties" in QEMU. On a real Power Mac the command prints
all the properties of the options node just fine.
I suppose it is possible to
fix this bug - if it is a bug. Another idea I have is to add a
completely different command-line option to QEMU just for
resolutions. The user could specify resolutions like this: -video-
resolutions 640x480,1024x768,1280x700.... This feature could place
the list of resolutions inside a property of the VGA device node. I
am betting the VGA driver could access this node and parse the list
of resolutions. So this: qemu -video-resolutions ---> OpenBIOS VGA
device node ---> VGA driver
Would anyone have another idea they would like to share?
As I said. Have OpenBIOS build the list of resolutions and put it in a
property (in binary, not ASCII form so the driver doesn't have to do
the mess it does now) in the DT node of the device itself.
I don't know about using binary. The way we do it now seems just fine.
I just need to figure out how to write to the /chosen node from the
QEMU command line. I found a function called OpenBIOS_set_var() in
openbios_firmware_abi.h, but it would require an address to write to.
So where do I find the address of the /chosen node....