Re: Huge console switching lags

[Paul Mundt]

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On Wed, Oct 03, 2001 at 09:58:30AM -0700, James Simmons wrote:
> > Well, there are indeed a few improvements to get with machine specific
> > optimisations on unaccelerated framebuffer.
> [snip]...
>=20
> Neat trick. Please note also that no read operations to the framebuffer
> are done by the fbcon layer. Such reads should be to the shadow buffers
> (vc_screenbuffer) instead. Reading the framebuffer is a userland operation
> and as such you really only tricks for reading in userland.=20
>=20
And while we're on the subject of architecture specific optimizations for
unaccelerated framebuffers (or framebuffers in general for that matter),
on SH4 you can remap the video memory area through a store queue and perform
all writes through the remapped store queue area (there are two store queue=
s,
each are 32bytes, and are flushed to the memory they were mapped to on a
prefetch instruction). This allows for very high speed writes to external
memory, as it was designed for.

Regards,

--=20
Paul Mundt <[e-mail]>
MontaVista Software, Inc.

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