Re: FB model basic issues (WAS: radeon, apertures & memory mapping)
flat view
From: Ville Syrjälä <syrjala@sci.fi>
Date: 2005-03-15 23:05:22
On Wed, Mar 16, 2005 at 09:44:19AM +1100, Benjamin Herrenschmidt wrote:
quoted
DirectFB assumes all memory outside var.yres_virtual * fix.line_length is preserved. A totally valid assumption in my opinion.Except that you can't know in advance how much fix.line_length will be. The "fix" isn't really "fixed". Different cards will have different requirements depending on the bit depth for example. On radeonfb, the line_length will vary due to alignment constraints related to the engine, or due to tiling, etc.... etc... So you basically don't know in advance what will be preserved... (And you can't, unless you start having all sort of card specific knowledge).
True. Currently DirectFB doesn't handle this correctly. But that could be easily fixed if only line_length wasn't totally misplaced. It really belongs to fb_var_screeninfo. We could first test the mode with FB_ACTIVATE_TEST and actually see how much memory it needs and could evict enough offscreen surfaces to make room before actually setting the mode. Currently it would need some guesswork. -- Ville Syrjälä syrjala@sci.fi http://www.sci.fi/~syrjala/ ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_ide95&alloc_id396&op=click