Re: [Linux-fbdev-devel] ruby on pm3/i386

[Sven L. <lu...@la...>]

On Tue, Sep 04, 2001 at 10:03:02AM -0700, James Simmons wrote:
> 
> > I added some printk's into the __fb_try_mode function, and the last message
> > displayed before the OOPS was SVEN : 19, which is just before the if line :
> > 
> >     printk ("SVEN : 18\n");
> >     var->vmode = mode->vmode
> >     printk ("SVEN : 19\n");
> >     if (info->fbops->fb_check_var)
> > 	err = info->fbops->fb_check_var(var, info);
> >     printk ("SVEN : 20\n");
> >     return !err;
> > }
> > 
> > So, i hope this gives you more information to tackle this bug.
> 
> That sounds like a bug in the check_var function. When I get the chance I
> will go threw the code. 


mmm, from my reading of the code and the bug and the stack trace and code
pointer, it seems that if fb_check_var was buggy, then the OOPS would happen
after the call to fb_check_var, and the code pointer returned by the OOPS
would be one inside the fb_check_var function.

my guess, but again, i didin't have time to look at it more in detail, would
be either info or info->fbops are null pointer. Or maybe even
info->fbops->fb_check_var is one, not sure if that would have the same
effect.

I will add some tests and printks here and report back.

But then maybe i misinterpreted the OOPS stuff, and it is possible that the
code pointer value is not the real one or something such ? i have no
experience in kernel debugging this kind of stuff.

Friendly,

Sven Luther