Re: Trying fbcon in dom1,but take_over_console fails...

[Deepak Manohar <mjdeepak@gmail.com>]

Hi Mark,

 Was any progress made on this? Were you able to get X to run in one
of the user domains?

 If not what is the status? Maybe you could give me some pointers on
what needs to be done?

Thanks
Deepak


On 4/8/05, Ian Pratt <m+Ian.Pratt@cl.cam.ac.uk> wrote:
> 
> > > I suspect you'd be better off getting the xencons to
> > register as ttyS0
> > > (xencons=ttyS0) so that it doesn't go anywhere near the
> > console, and
> > > compile in VT, VT_CONSOLE and DUMMY_CONSOLE.
> > Tried that, as well as disabling VGA_CONSOLE, but no
> > improvements :-(:-( however, when built as a module, it is
> > somewhat easier to debug this problem in fbcon, since dom1 is
> > still running after it segfaults, and I can still use dmesg
> > to see the printk's (strange that they don't appear on the
> > console...).
> 
> Do you actually need fbcon? You don't need it to run X in most setups.
> 
> [If you want the printk's to come out on the console, use the KERN_ALERT prefix]
> 
> 
> Ian
> 
> > >
> > > Please let us know how you get on.
> >
> > Ok, here's what I found so far:
> >
> > Using printk statements, I was able to find the culprit, it
> > seems to be the vc pointer which is not initialised properly.
> >
> > Here's the piece of code (from fbcon_startup):
> >
> > /* Setup default font */
> > if (!p->fontdata) {
> > if (!fontname[0] || !(font = find_font(fontname)))
> > font = get_default_font(info->var.xres,
> > info->var.yres);
> >
> > DPRINTK("fbcon_startup: ca\n");
> >
> > vc->vc_font.width = font->width;
> > vc->vc_font.height = font->height;
> > vc->vc_font.data = p->fontdata = font->data;
> > vc->vc_font.charcount = 256; /* FIXME Need
> > to support more fonts */
> >
> > DPRINTK("fbcon_startup: cb\n");
> >
> > }
> >
> > And the oops occurs between the two DPRINTK's...
> > So I added a check at startup:
> >
> > static const char *fbcon_startup(void)
> > {
> > const char *display_desc = "frame buffer device";
> > struct display *p = &fb_display[fg_console];
> > struct vc_data *vc = vc_cons[fg_console].d;
> > struct font_desc *font = NULL;
> > struct module *owner;
> > struct fb_info *info = NULL;
> > struct fbcon_ops *ops;
> > int rows, cols;
> > int irqres;
> >
> > DPRINTK("fbcon_startup... fg_console: %d, vc:
> > %d\n",fg_console,vc);
> >
> > This prints 0 for the fg_console (not necessarely a problem)
> > as well as vc...
> > which is defenately a problem since it is dereferenced later!
> >
> > Seems like the vc_cons is not setup right, I'll have to take
> > a look into vt.c I guess.
> > Could this be due to the missing ps/2 port on domU (since
> > they are assigned to dom0)?
> >
> > Will report back when I know more.
> >
> >
> > Regards,
> > Mark.
> >
> > _______________________________________________
> > Xen-devel mailing list
> > Xen-devel@lists.xensource.com
> > http://lists.xensource.com/xen-devel
> >
> 
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