Re: scrollmode, accel_flags, fbcon.c ...

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

> 
> These are hints for fbcon to use different types of scrolling. Using special
> hardware features is usually faster than doing dumb copies.

Yes, that all make sense, but there isn't a simple way for the fbdev
to set that now in 2.6 since it's in struct display which is now local
to fbcon. fbcon itself will initialize that to some value picked based
on the default var accel flags but I don't like that, espeically since
I think those flags should be deprecated.

> It is (was?) mainly a flag to indicate the fbdev uses and thus owns the accel
> engine. Userspace cannot mmap the MMIO registers and use the accel engine
> unless it first clears this flag. It can also be used just to disable the accel
> engine.

I know, I used them this way in 2.4, but with the 2.6 changes, they
becaome mostly unmanageable.

> These days it seems like vt_cons[vc->vc_num]->vc_mode == KD_TEXT seems to
> indicate the fbdev owns the accel engine, right James?

Yes.

Ben.




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