Re: Finally found why 2.6.x has troubles with taking over vgacon

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

On Sunday 04 July 2004 03:56, Petr Vandrovec wrote:
> Hi Antonio,
>   yesterday I finally found why 2.6.x has problems with taking over vgacon.
> Problem is that take_over_console does:
>
>
>   if (IS_VISIBLE)
>     save_screen(i);
>   ...
>   visual_init(i, 0);
>   ...
>
> so code nicely saves screen contents, and calls visual_init, which calls
> fbcon's init, which in turn can issue vc_resize. And this vc_resize will
> trigger read from vc->vc_origin. But vc_origin still points to videomemory,
> not to the buffer where save_screen() copied its data.
>
>   In my fbcon
> (http://platan.vc.cvut.cz/ftp/pub/linux/matrox-latest/matroxfb-2.6.7-c1784.
>tar.gz) after I put
>
>   origin = visual_origin = screenbuf;
>
> below save_screen call, and removed clearing screen from radeon sources
> both radeonfb and matroxfb were able to take over vgacon, without any
> randomly colored characters on screen.

Petr, excellent detective work :-) .  I was suspecting vc_resize() was partly
causing the corruption, but never knew the reason until you pointed this

>
>   It also allows for removing special fillrect clear, as now code
> which clears upper few lines of logo area actually works...

Yes, I can now finally remove that ugly fillrect code.  I'll submit a patch on the
next batch of mm or BK release. 

Thanks.

Tony




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