[okl4-developer] okl4: system hangs if I use virtual_lcd_get_mode

[Geoffrey Lee]

On Thu, Aug 14, 2008 at 03:32:55PM +0200, Dennis Gessner wrote:
> Hello everyone,
> hello Nelson,

Hi Dennis

> 
> 
> is there any reason, why okl4 -hangs- if I use the function
> "virtual_lcd_get_mode" inside "init_lcd" (regarding your tutorial: Using
> A Virtual Device"?
> 
> Here is the exact call:
> 
> "virtual_lcd_get_mode(lcd->server, lcd->obj, &lcd->control->xres,
> &lcd->control->yres, &lcd->control->bpp, NULL);"
> 
> It's not even possible to enter the KDB manually if I enter 	
> 
> "L4_KDB_Enter("Please please - print this...");"

While I do not know what the specific problem is and hence cannot
help you with your immediate problem, L4_KDB_Enter() will break 
you into the debugger.  This means that prior to system hang you 
should be dropped into the debugger.  Since this is not happening, I 
suspect there may be something else that is causing this problem.

Note that the system is not hung, it is alive and well doing 
work, as you have noted:


> 
> one line above the other one. If I hit ESC in a VERY fast rate, it's
> possible to enter the KDB. The funny thing (for me) is, it looks like
> the problem is the call of the function itself, not what is inside the
> function (for testing - I commented out everything inside
> "virtual_lcd_get_mode").
> 
> Inside the KDB - if I /tracebuffer and dump (in the situation the system
> hangs) I see only three different lines (repeating in a fast rate):
> 
> INTERRUPT: 0000c001, 80000000
> SYSCALL_INTERRUPT_CONTROL
> SYSCALL_IPC: 0000c001, 00000000, ffffffff


So, the system seems to have gotten an interrupt, is trying 
to handle it, but somehow it got itself stuck in a loop.  The 
ESC hotkey is polling which may explain why it seems non-repsonsive,
as the system is busy doing work.

	-gl

> 
> It looks like my function (init_lcd) has not the necessary rights to use
> the function "virtual_lcd_get_mode". What does okl4 internally do when a
> function is called? I did everything else as described in your tutorial
> (http://wiki.ok-labs.com/DriverFramework).
> 
> Best regards,
> Dennis
> 
> (Using okl4 2.1.1-patch9 with gta01 emulated inside qemu)
> 
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