help adding extended text modes in Hypervisor

help adding extended text modes in Hypervisor

[Edward Middleton]

I am trying to get the hypervisor to run in an extended text modes,
specifically 132x44 text mode. I don't really know much about
setting video modes so there may be something inherently broken with
my approach. I have done some Linux device drivers programming and a
little assembler but am probably out of my depth. I have tried
putting the correct VGA register settings (taken after booting into
132x44 text mode vga=0x133 in regular Linux) for this mode into

xen-2.0/xen/drivers/char/console.c
static void init_vga(void)
{
...
static unsigned char regs[]

and setting the #define COLUMNS,LINES

This failed resulted in the monitor switching off at boot, though it
did still boot.

I also looked into using the Linux video initialization routine in
(line 110 linux/arch/i386/boot/video.S). Firstly in
(xen-2.0/xen/arch/x86/boot/x86_32.S) but this doesn't look like the
write place.

I guess video.S corresponds to the init_vga function
(xen-2.0/xen/drivers/char/console.c) the Xen Hypervisor. In (line 398
linux/arch/i386/boot/setup.S) where the video routine is called the
comment states that %ds must be pointing to the bootsector, what is
this for? how would you do this? Near the end setup.S the video.S is
included and at the end a comment "after this point there is some free
space which is used by by the video mode handling code". Is this what
the %ds is being used for?

Any help or advice would be appreciated.

Edward Middleton



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Re: help adding extended text modes in Hypervisor

[Ian Pratt]

> I am trying to get the hypervisor to run in an extended text modes,
> specifically 132x44 text mode. I don't really know much about
> setting video modes so there may be something inherently broken with
> my approach. I have done some Linux device drivers programming and a
> little assembler but am probably out of my depth. I have tried
> putting the correct VGA register settings (taken after booting into
> 132x44 text mode vga=0x133 in regular Linux) for this mode into


Feel free to say 'yes', but is it really worth the effort? 

When dom0 takes over the VGA console (which is the default mode
of operation) you can arrange to put it into whatever mode you
like; you just won't get the initial boot messages from Xen in
the extended text mode.

ian


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Re: help adding extended text modes in Hypervisor

[Edward Middleton]

Ian Pratt wrote:

>>I am trying to get the hypervisor to run in an extended text modes,
>>specifically 132x44 text mode. I don't really know much about
>>setting video modes so there may be something inherently broken with
>>my approach. I have done some Linux device drivers programming and a
>>little assembler but am probably out of my depth. I have tried
>>putting the correct VGA register settings (taken after booting into
>>132x44 text mode vga=0x133 in regular Linux) for this mode into
>>    
>>
>Feel free to say 'yes', but is it really worth the effort? 
>  
>
Ultimately it would be good being able to see most of the boot messages 
while booting.  I guess it really depends on whether its possible to get 
video.S to work (allow the same mode selection as Linux) with a simple 
hack or weather it is much more involved.

>When dom0 takes over the VGA console (which is the default mode
>of operation) you can arrange to put it into whatever mode you
>like; you just won't get the initial boot messages from Xen in
>the extended text mode.
>  
>
I was looking at modifying the hypervisor because I couldn't get this to 
work and couldn't find a specific reference stating it was possible.  I 
have the following lines in grub and it doesn't set the video mode

title Xen 2.0 / XenLinux 2.6.9
root (hd0,0)
kernel /boot/xen.gz dom0_mem=131072 console=vga
module /boot/vmlinuz-2.6.9-xen0 root=/dev/sda6 vga=0x133

I have tried various permutations of this with no success.

Thanks

Edward


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Re: help adding extended text modes in Hypervisor

[Jared Rhine]

> Edward> I am trying to get the hypervisor to run in an extended text modes,

> Ian> When dom0 takes over the VGA console (which is the default mode
> >of operation) you can arrange to put it into whatever mode you
> >like; you just won't get the initial boot messages from Xen in
> >the extended text mode.

> I was looking at modifying the hypervisor because I couldn't get this to 
> work and couldn't find a specific reference stating it was possible.

I too, have failed to set any vga mode for any Xen installation.  Could
the developers confirm 1 more time that it "works for them" (if indeed)
and we can try to characterize the bug more.

> module /boot/vmlinuz-2.6.9-xen0 root=/dev/sda6 vga=0x133

I too have tried various vga variants without any success.

-- 
Jared Rhine <jared@wordzoo.com>



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VGA extended text mode on XenCD not functional

[Jared Rhine]

[Jared == jared@wordzoo.com on Sun, 02 Jan 2005 06:20:21 -0800]

  Edward> I am trying to get the hypervisor to run in an extended text
  Edward> modes,

  Ian> When dom0 takes over the VGA console (which is the default mode
  Ian> of operation) you can arrange to put it into whatever mode you
  Ian> like; you just won't get the initial boot messages from Xen in
  Ian> the extended text mode.

  Edward> I was looking at modifying the hypervisor because I couldn't
  Edward> get this to work and couldn't find a specific reference
  Edward> stating it was possible.

  Jared> I too, have failed to set any vga mode for any Xen
  Jared> installation.  Could the developers confirm 1 more time that
  Jared> it "works for them" (if indeed) and we can try to
  Jared> characterize the bug more.

Perhaps this is a dead issue, but I put an example 'vga=791'
configuration onto the XenCD boot menu, which as far as I can tell
here, does not function as Ian describes.  I'd love to get this
feature working.

-- jared@wordzoo.com

"Tiger gotta hunt.  Bird gotta fly.
 Man gotta sit and wonder why, why, why.
 Tiger gotta sleep.  Bird gotta land.
 Man gotta tell himself he understand." -- Kurt Vonnegut Jr.


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VGA extended text modes

[Jared Rhine]

  Edward> I am trying to get the hypervisor to run in an extended text
  Edward> modes,

  Ian> When dom0 takes over the VGA console (which is the default mode
  Ian> of operation) you can arrange to put it into whatever mode you
  Ian> like; you just won't get the initial boot messages from Xen in
  Ian> the extended text mode.

  Edward> I was looking at modifying the hypervisor because I couldn't
  Edward> get this to work and couldn't find a specific reference
  Edward> stating it was possible.

  Jared> I too, have failed to set any vga mode for any Xen
  Jared> installation.  Could the developers confirm 1 more time that
  Jared> it "works for them" (if indeed) and we can try to
  Jared> characterize the bug more.

Apologies for following up to this thread for the third time, but near
as I can tell, this is an open issue.

Can anyone (developers especially) confirm or deny operation of
extended VGA modes in dom0?

XenCD comes with a handy boot menu item to serve as a repeatable test
case :)

-- jared@wordzoo.com

War is God's way of teaching Americans geography. -Ambrose Bierce


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Re: VGA extended text modes

[B.G. Bruce]

I can't speak for anyone else but I know that at one time (about 2-3
weeks ago) a vga=ask allowed me to get into 80x60 mode under xen0 -
ultimately I swapped over to running intelfb in 1280x1024 but I know
that at least on my equipment (and my kernels) both of these work as 
per usual.

B.


On Sat, 2005-02-26 at 04:39, Jared Rhine wrote:
>   Edward> I am trying to get the hypervisor to run in an extended text
>   Edward> modes,
> 
>   Ian> When dom0 takes over the VGA console (which is the default mode
>   Ian> of operation) you can arrange to put it into whatever mode you
>   Ian> like; you just won't get the initial boot messages from Xen in
>   Ian> the extended text mode.
> 
>   Edward> I was looking at modifying the hypervisor because I couldn't
>   Edward> get this to work and couldn't find a specific reference
>   Edward> stating it was possible.
> 
>   Jared> I too, have failed to set any vga mode for any Xen
>   Jared> installation.  Could the developers confirm 1 more time that
>   Jared> it "works for them" (if indeed) and we can try to
>   Jared> characterize the bug more.
> 
> Apologies for following up to this thread for the third time, but near
> as I can tell, this is an open issue.
> 
> Can anyone (developers especially) confirm or deny operation of
> extended VGA modes in dom0?
> 
> XenCD comes with a handy boot menu item to serve as a repeatable test
> case :)
> 
> -- jared@wordzoo.com
> 
> War is God's way of teaching Americans geography. -Ambrose Bierce
> 
> 
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> Xen-devel mailing list
> Xen-devel@lists.sourceforge.net
> https://lists.sourceforge.net/lists/listinfo/xen-devel
> 


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Re: help adding extended text modes in Hypervisor

[Luciano Miguel Ferreira Rocha]

On Thu, Dec 16, 2004 at 03:10:22AM +0000, Ian Pratt wrote:
> > I am trying to get the hypervisor to run in an extended text modes,
> > specifically 132x44 text mode. I don't really know much about
> > setting video modes so there may be something inherently broken with
> > my approach. I have done some Linux device drivers programming and a
> > little assembler but am probably out of my depth. I have tried
> > putting the correct VGA register settings (taken after booting into
> > 132x44 text mode vga=0x133 in regular Linux) for this mode into
> 
> 
> Feel free to say 'yes', but is it really worth the effort? 
> 
> When dom0 takes over the VGA console (which is the default mode
> of operation) you can arrange to put it into whatever mode you
> like; you just won't get the initial boot messages from Xen in
> the extended text mode.

Is there something like dmesg for xen?

Regards,
Luciano Rocha


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Re: help adding extended text modes in Hypervisor

[Derrik Pates]

Luciano Miguel Ferreira Rocha wrote:
> Is there something like dmesg for xen?

'xm dmesg' will show the Xen hypervisor's queued log messages.

-- 
Derrik Pates
dpates@dsdk12.net


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RE: VGA extended text modes

[Ian Pratt]

>   Jared> I too, have failed to set any vga mode for any Xen
>   Jared> installation.  Could the developers confirm 1 more time that
>   Jared> it "works for them" (if indeed) and we can try to
>   Jared> characterize the bug more.
> 
> Apologies for following up to this thread for the third time, but near
> as I can tell, this is an open issue.
> 
> Can anyone (developers especially) confirm or deny operation of
> extended VGA modes in dom0?

To my knowledge I don't think any of us use extended VGA text modes. I
think we're just rather 'surprised' that it doesn't just work. After Xen
has relinguished the VGA console, domain 0 should be able to use it
however it pleases. 

However, how does dom0 set the extended text mode? I presume it doesn't
use a BIOS call. Perhaps it can't cope with the scroll state we leave
the console in?
The former would be a huge pain. Anything else is probably trivially
fixed once the cause is discovered.

Ian


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Re: VGA extended text modes

[Gerd Knorr]

"Ian Pratt" <m+Ian.Pratt@cl.cam.ac.uk> writes:

> However, how does dom0 set the extended text mode? I presume it doesn't
> use a BIOS call.

Linux uses vesa bios calls in the 16bit startup code, at least for the
stuff settable via vga="...".  Mode info is passed to 32bit code in
struct screen_info (see Documentation/i386/zero-page.txt).  Thats why
the vga argument needs special treatment by the boot loaders, they
can't just pass it on on the kernel command line like most other args.
They have to set a byte in the kernel's boot sector for that.  See
also "man rdev".  That is really old stuff from the days you have
booted your new linux kernel using "cat zImage > /dev/fd0 && reboot".

For just more text lines you can simply load a smaller font than the
default one somewhere in the dom0 boot scripts to have the same
effect.  That doesn't work for 132col txt modes or graphic modes (=>
vesafb) though.

  Gerd

-- 
#define printk(args...) fprintf(stderr, ## args)


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