newcons fb driver

[Adrian Chadd]

.. i'm pretty sure there was a reason for why it's done in byte sizes.
Maybe speak to phk?


-a

On 2 March 2014 08:55,  <jhibbits at freebsd.org> wrote:
> I've been looking into the slowness of the newcons framebuffer backend,
> and after discussing with Nathan Whitehorn, we've determined that the
> slowness is caused by single byte writes to the framebuffer, which are
> very much suboptimal.  His conclusion is that, on nVidia hardware, the
> card first performs a read, a very slow operation on the hardware, then
> a single-byte write, and I'm thinking the same.  So, to accomodate this
> limitation, I have a question and proposal:
>
> (q) From looking at the code, it appears to support, to some degree, a
> background image (the character blitting uses a mask, it doesn't just
> write background in that mask).  Is this truly the case?
>
> (p) If it is the case that it supports a background image, I'm thinking
> it would make sense to buffer the framebuffer, such that we write to
> the internal representation, and blit whole words or lines at a time
> to the hardware. With an 8-bit buffer, at 1920x1080 (common resolution)
> we would be using approximately 2MB for the buffer.  On memory
> constrained devices this can be quite significant, so it becomes a
> tradeoff.
>
> Thoughts?
>
> - Justin
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