Re: Booting arguments for NetBSD under qemu

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

http://mail-index.netbsd.org/netbsd-users/2014/04/thread1.html#014442


On 29 April 2014 12:14, Michael <macallan%netbsd.org@localhost> wrote:
> Hello,
>
> On Wed, 23 Apr 2014 23:41:33 +0100
> David Brownlee <abs%absd.org@localhost> wrote:
>
>> 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?
>
> Because tcx was never updated to return a match score higher than 1.
> I'll fix that in a minute.
> Frankly I'm surprised that people actually use genfb at sbus, given its
> lack of colour map control ( thanks to OBP < 3 not having a standard
> method to do it... ) ;)

I suspect that people have not chosen to do so - they are just picking
up on the default behaviour and didn't know there was a choice :)

With your above change qemu has consistent behaviour with or without
-nographic (which is good). Of course both of them now panic due to
qemu's incomplete implementation, which is less good... but one item
at a time...

>> 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'
>
> And that matches real OBP / OF - no need for the firmware to map the
> framebuffer if it isn't going to scribble into it.
> So qemu doesn't emulate a complete tcx in the -nographics case but it
> doesn't really tell us. As a workaround I could check
> for /packages/grubfs-files and skip tcx if that node is present and tcx
> isn't the console. Looks more like a bug in qemu though.

Should someone ping Mark Cave-Ayland <mark.cave-ayland%ilande.co.uk@localhost ?
I'm happy to just cc him into this thread with a few words, but if
someone else has already spoken to him about other items then it may
make more sense for them to raise it...