Re: Detect switching to X?

["Antonino A. Daplas" <adaplas@gmail.com>]

Knut Petersen wrote:
> Hi Tony
> 
>>>
>>> Is there any way for a framebuffer driver to detect that a switch
>>> to X is in progress?
>>>   
>>
>> None, although fbcon will detect switches from KD_TEXT<->KD_GRAPHICS. I'm
>> thinking of adding optional fb_save_state() and fb_restore_state() hooks
>> which fbcon will call before going to KD_TEXT and before going to
>> KD_GRAPHICS respectively.
>>
>> I have the code in my development tree since one of the drivers does
>> not work with the experimental DRI driver. The DRI driver does not fully
>> restore its hardware state so the fbdev driver has to do the restore
>> for it.
>>
>>  
>>
> Please do submit that code as a patch to the main kernel tree as soon as
> possible.
> 

The patch is not really palatable.  It is a patch that attempts to fix
bugs in X, not fbcon.  Unless the problem is really widespread, then maybe
I'll go for it for mainline.

> I cannot take advantage of the full memory reserved for the
> cyberblade/i1 because
> the trident X driver only knows about the vga style way of setting the
> screen start
> address. The other way involves the usage of the register at GEBase +
> 0x10, but
> that disables the vga style setting completely.
> 
> There is one alternative way: I could hook somewhere into a periodically
> called
> interrupt, put some insane value into the vga style regs and check for a
> change.
> Then I would assume that X has switched to KD_GRAPHICS and enable the
> vga style again.

You need not do that (do a periodic check).  A set_par() will always be
called by fbcon whenever the console transitions from KD_GRAPHICS to
KD_TEXT.  So all you need to do is possibly check some register that says
the hardware is in legacy mode.

Tony


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