Re: [PATCH] drm: Initial KMS driver for AST (ASpeed Technologies) 2000 series

[Alan Cox <alan@lxorguk.ukuu.org.uk>]

> ends up in the in-VRAM object. I'll have to add defio support to make this work
> properly now that I think about it a bit more, but defio isn't a major
> amount of work.

Ok

> fbdev objects once exposed to userspace or to fbcon, thanks to some wonderful
> API design way back, the mmaps on the fbdev device are direct to the VRAM
> physical pages. Can't tear them down and move them into system RAM pages
> at all easily.

Thats not strictly true. They can move mapping if the locking is right
and the helpers handle it because you can invalidate the pages in the
userspace mappings and they will get faulted back with the new ones.

> Because I'm not 100% sure nothing will get written to it, and if

Fair point.

> something gets written
> to it I'd rather not have to complicate the oops printing to have to
> page in memory
> from disk, when it might be the disk that caused the oops.

If the box was horked that way then you are going to fail to migrate the
graphical frame buffer out in order to go into text mode to print the
oops. Probably safest any oops hits the current visible object ?

Alan