Proposal for a low-level Linux display framework

Alan Cox alan at lxorguk.ukuu.org.uk
Thu Sep 15 12:05:14 PDT 2011


> What is your problem with discontigous framebuffers? (I assume discontigous
> refers to the pages the framebuffer is composed of)
> Sounds to me like you should implement your own fb_mmap and either map it
> contigous to screen_base or implement your own fb_read/write.
> In theory you could even have each pixel at a completely different memory
> location although some userspace wouldn't be happy when it could no longer mmap
> the framebuffer.

The mmap side is trivial, the problem is that the fb layer default
implementations of blits, fills etc only work on a kernel linear frame
buffer. And (for example) there is not enough linear stolen memory on
some Intel video for a 1080p console on HDMI even though the hardware is
perfectly capable of using an HDTV as its monitor. Nor - on a 32bit box-
is there enough space to vremap it.

Alan


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