Re: cg14 vesa (modes) project on github

[Bob Breuer <bbreuer711%gmail.com@localhost>]

On Wed, Jan 7, 2026 at 11:46 AM Andrew Randrianasulu
<randrianasulu%gmail.com@localhost> wrote:
>
> On Wed, Jan 7, 2026 at 8:40 PM Malte Dehling <mdehling%gmail.com@localhost> wrote:
> >
> > Hi Andrew,
> >
> > I've only tested the prom on physical hardware, and I haven't been able to get qemu to work with an ss20 and original prom recently.  Would love to hear if you make progress on this!
>
> well, for me setting -cpu to something like
>
> "TI SuperSparc 50"

As I remember, the Qemu SuperSparc II implementation doesn't support
one of the features used by the original OBP roms.

>
> work, at least i see logo and can enter probe-scisi.
>
> Note, this is more like qemu 9.2.50 as Artyom created it 9 months ago,
> not really recent qemu git (10.x, 11.x)
>
> https://youtu.be/wCFBvzVCVMk - short vid of whole thing booting
>

I didn't notice that Artyom rebased my cg14 patches.  I also have a
separate branch where I implemented the DBRI audio device.

> >
> > IIRC, qemu has resolutions hard coded in, but I may be wrong about this.

Is there any particular resolution that you are looking for?

The emulated cg14 was flexible enough to handle any resolution that
could be programmed.  However, the startup resolution is limited by
the monitor ID bits.  The cg14_set_monitor_id() function translates
the Qemu command line resolution to a monitor ID for a nearby OBP
resolution.  In addition to 1152x900, the resolutions of 1280x1024 and
1600x1280 should also work by default.

Bob


> >
> > Cheers,
> > Malte
> >
> >
> > On Wed, Jan 7, 2026, 9:31 AM Andrew Randrianasulu <randrianasulu%gmail.com@localhost> wrote:
> >>
> >> On Wed, Jan 7, 2026 at 8:00 PM Andrew Randrianasulu
> >> <randrianasulu%gmail.com@localhost> wrote:
> >> >
> >> > Was looking for Sparcstation-20 proms to test with cg14 enabled qemu
> >> >
> >> > found this project;
> >> >
> >> > https://github.com/mdehling/cg14-vesa-mod
> >> >
> >> > https://github.com/artyom-tarasenko/qemu/ - branch cg14
> >> > https://github.com/artyom-tarasenko/qemu/commit/1b1d8b87619e613b059766e6e54687b027fb6e3f.diff
> >> >
> >> > https://github.com/artyom-tarasenko/qemu/commit/b297821755e68381e7753d877a7912bebe9271d8.diff
> >> >
> >> > but device cg14 not on list so you need to start it like this:
> >> >
> >> > build/qemu-system-sparc -M SS-20 -g 1152x900
> >> > cg14_realizefn 1152, 900
> >> >
> >> > Of course default openbios does not know how to output to that, so I'm
> >> > trying this Sun PROM now ...
> >>
> >>
> >> It tries to boot my NetBSD install but it faults somewhere along the way:
> >>
> >>  build/qemu-system-sparc -M SS-20 -g 1152x900 -bios
> >> ~/Desktop/ss20-2.25.bin  -cpu "TI SuperSparc 50" -hda
> >> /mnt/zip/home/guest/QEMU/sparc-netbsd-15g-compressed-r1.qcow2
> >> cg14_realizefn 1152, 900
> >> CG14: control register (0x5a) has unimplemented bits set
> >> CG14: readb from reg 1000
> >> CG14: writeb 0x00 to reg 1000
> >> CG14: writeb 0x01 to reg 1000
> >> CG14: readb from reg 1000
> >> CG14: readb from reg 1001
> >> CG14: writeb 0x01 to reg d
> >> CG14: readl 00000000 from reg 20c
> >> CG14: writeb 0x02 to reg 100
> >> CG14: readl 00000000 from reg 20c
> >> CG14: readb from reg 200b
> >> CG14: readb from reg c
> >> CG14: writeb 0x00 to reg c
> >> CG14: writeb 0x02 to reg 100
> >> CG14: readl 00000000 from reg 20c
> >> CG14: readb from reg 200b
> >> CG14: readb from reg c
> >> CG14: writeb 0x00 to reg c
> >>
> >> https://mastodon.online/@Andrew_R/115854999356998946