Re: booting linux 2.6 in qemu-system-ppc

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Re: booting linux 2.6 in qemu-system-ppc

Benjamin Herrenschmidt

> console=ttyS0 console=tty0
> Note that the Open-Firmware frame-buffer support is broken in many 2.6
> kernels (I mean on real Macs)

How so ?

> and that most distributions install CDROM
> don't have support for PC serial ports. Then, to be able to have video
> console with any 2.6 based distribution, I'm afraid we'll need to have
> an ATI Radeon emulation.
> You can also notice that we don't emulation Mac serial ports, in Qemu.
>



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Re: booting linux 2.6 in qemu-system-ppc

John Reiser
>>Note that the Open-Firmware frame-buffer support is broken in many 2.6
>>kernels (I mean on real Macs)

> How so ?

Well, in Fedora Core 4 test 3 (kernels 2.6.11.* and 2.6.12-rc*):
video switching at boot from yaboot with Open Firmware to Tux with
scrolling VGA text is problematic, and switching video from X11 to
VGA-style text virtual consoles does not work at all on my Mac mini.
[On the same hardware, Mac OS X has no problems at all.]  Perhaps
this is just a fumbled handoff _from_ Open Firmware video to direct
video on the hardware, but "support" certainly includes that.

https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=156824
https://bugzilla.redhat.com/bugzilla/show_bug.cgi?id=156826
https://bugs.freedesktop.org/show_bug.cgi?id=3280

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Re: booting linux 2.6 in qemu-system-ppc

J. Mayer
In reply to this post by Benjamin Herrenschmidt
On Mon, 2005-05-23 at 10:31 +1000, Benjamin Herrenschmidt wrote:
> > console=ttyS0 console=tty0
> > Note that the Open-Firmware frame-buffer support is broken in many 2.6
> > kernels (I mean on real Macs)
>
> How so ?

Well, there have been many issues with frame-buffer in 2.6, not only on
Mac platform.
With Open-Firmware frame buffer, I remember the first 2.6 kernels had no
fb output at all.
Then came kernels that could display a Tux penguin in psychadelic
colors, I guess it was drawing in 16 bits mode when the OF frame-buffer
is 15 bits.
This has been solved in more recent kernels. I don't remember in which
version it was fixed (but I think around 2.6.5 or 2.6.6).
I can easily reproduce this on my Ibook and on my Apple Network Server,
which means it's not a hardware-dependant bug (Ibook 2 has an ATI
graphic card, ANS is cirrus-logic) nor it's specific to some OF version
(ANS one is really old...).

There is now another bug with qemu: with recent 2.6 kernels, the
frame-buffer is recognized and console is working but it only draws
characters black on black background, even if I send escape sequences to
change the drawing color. Note that the penguin is well drawn, in those
cases.
If you have an idea of what can cause this, I'd be glad to know it ;-)

[...]

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J. Mayer <[hidden email]>
Never organized



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Re: booting linux 2.6 in qemu-system-ppc

Benjamin Herrenschmidt
On Mon, 2005-05-23 at 12:47 +0200, J. Mayer wrote:

> On Mon, 2005-05-23 at 10:31 +1000, Benjamin Herrenschmidt wrote:
> > > console=ttyS0 console=tty0
> > > Note that the Open-Firmware frame-buffer support is broken in many 2.6
> > > kernels (I mean on real Macs)
> >
> > How so ?
>
> Well, there have been many issues with frame-buffer in 2.6, not only on
> Mac platform.
> With Open-Firmware frame buffer, I remember the first 2.6 kernels had no
> fb output at all.
> Then came kernels that could display a Tux penguin in psychadelic
> colors, I guess it was drawing in 16 bits mode when the OF frame-buffer
> is 15 bits.
> This has been solved in more recent kernels. I don't remember in which
> version it was fixed (but I think around 2.6.5 or 2.6.6).
> I can easily reproduce this on my Ibook and on my Apple Network Server,
> which means it's not a hardware-dependant bug (Ibook 2 has an ATI
> graphic card, ANS is cirrus-logic) nor it's specific to some OF version
> (ANS one is really old...).
>
> There is now another bug with qemu: with recent 2.6 kernels, the
> frame-buffer is recognized and console is working but it only draws
> characters black on black background, even if I send escape sequences to
> change the drawing color. Note that the penguin is well drawn, in those
> cases.
> If you have an idea of what can cause this, I'd be glad to know it ;-)

I would say the palette isn't set properly ...

Ben.




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Re: booting linux 2.6 in qemu-system-ppc

J. Mayer
On Mon, 2005-05-23 at 20:51 +1000, Benjamin Herrenschmidt wrote:

> On Mon, 2005-05-23 at 12:47 +0200, J. Mayer wrote:
> > On Mon, 2005-05-23 at 10:31 +1000, Benjamin Herrenschmidt wrote:
> > > > console=ttyS0 console=tty0
> > > > Note that the Open-Firmware frame-buffer support is broken in many 2.6
> > > > kernels (I mean on real Macs)
> > >
> > > How so ?
> >
> > Well, there have been many issues with frame-buffer in 2.6, not only on
> > Mac platform.
> > With Open-Firmware frame buffer, I remember the first 2.6 kernels had no
> > fb output at all.
> > Then came kernels that could display a Tux penguin in psychadelic
> > colors, I guess it was drawing in 16 bits mode when the OF frame-buffer
> > is 15 bits.
> > This has been solved in more recent kernels. I don't remember in which
> > version it was fixed (but I think around 2.6.5 or 2.6.6).
> > I can easily reproduce this on my Ibook and on my Apple Network Server,
> > which means it's not a hardware-dependant bug (Ibook 2 has an ATI
> > graphic card, ANS is cirrus-logic) nor it's specific to some OF version
> > (ANS one is really old...).
> >
> > There is now another bug with qemu: with recent 2.6 kernels, the
> > frame-buffer is recognized and console is working but it only draws
> > characters black on black background, even if I send escape sequences to
> > change the drawing color. Note that the penguin is well drawn, in those
> > cases.
> > If you have an idea of what can cause this, I'd be glad to know it ;-)
>
> I would say the palette isn't set properly ...

Right, is this set according to some OF properties (which could be a
cause of the bug) ?
I didn't find anything like this in OF fb code, but I may have missed
it....

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J. Mayer <[hidden email]>
Never organized



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Re: booting linux 2.6 in qemu-system-ppc

Benjamin Herrenschmidt



> Right, is this set according to some OF properties (which could be a
> cause of the bug) ?
> I didn't find anything like this in OF fb code, but I may have missed
> it....

prom_init() sets it using calls to OF fb driver setcolreg method.

Ben.




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