Re: Booting arguments for NetBSD under qemu

[David Brownlee <abs%absd.org@localhost>]

On 23 April 2014 16:13, Michael <macallan%netbsd.org@localhost> wrote:
> Hello,
>
> On Wed, 23 Apr 2014 15:39:42 +0100
> David Brownlee <abs%absd.org@localhost> wrote:
>
>> On 23 April 2014 11:32, Michael <macallan%netbsd.org@localhost> wrote:
>> > Hello,
>> >
>> > On Mon, 21 Apr 2014 19:32:19 +0100
>> > David Brownlee <abs%absd.org@localhost> wrote:
>> >
>> >> tcx0 at sbus0 slot 3 offset 0x800000 level 5 (ipl 9) (8bit only
>> >> TCX)tcx0: SUNW,tcx, 1024 x 768, id 0, rev 0, sense 0system[0]: trap
>> >> 0x29: pc=0xf00abe2c sfsr=0xb6 sfva=0x8fc
>> >> cpu0: data fault: pc=0xf00abe2c addr=0x8fc
>> >> sfsr=0xb6<PERR=0x0,LVL=0x0,AT=0x5,FT=0x5,FAV,OW>
>> >> panic: kernel fault
>> >
>> > That's the TCX's hardware cursor position register. Looks like qemu
>> > doesn't actually emulate that part of TCX.
>>
>> The system boots fine when qemu is run "not -nographic", though it
>> attaches genfb so the tcx specific hardware is not touched...
>> presumably it might be expected to panic if someone runs X in that
>> case?
>
> No, the xf86-video-suntcx driver won't attach without the kernel driver.
>
>> Should NetBSD be attaching tcx0 rather then genfb0 in the "not -nographic"?
>
> If in the "not -nographics" everything works, why not?

My question was more "why does NetBSD try to attach tcx0 on a machine
with serial console  and genfb on the same machine with graphical
console (albeit an emulated qemu machine). Should it not be trying to
attach tcx in box cases?

>> >> So an immediate workaround to enable running NetBSD-6.x would be to
>> >> update to qemu-2.0.0 and use "-vga cg3", meanwhile someone can have a
>> >> poke at NetBSD and see why -nographic and emulated tcx have issues...
>> >> :)
>> >
>> > See above. A proper workaround would be to either add the missing bits
>> > to qemu or find a way for our tcx driver to detect qemu and skip the
>> > hardware that's not actually emulated.
>>
>> Would the output of "ofctl -p" give any clues (attached). This is from
>> a "not -nographic" run from a HEAD kernel.
>
> Actually the diff between "-nographics" and "not -nographics" would be more 
> interesting.

That we can do. The "-nographics" case is with a kernel compiled without tcx0:
- http://sync.absd.org/sparc/qemu-ofctl-nographic.txt
- http://sync.absd.org/sparc/qemu-ofctl.txt

Thats... clever - the only difference to the tcx properties in the
-nographics case is that it is missing 'address'