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Re: NetBSD 5.0 and SPARCstation 5 not a lucky combination
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On Jul 28, 2009, at 1:01 AM, der Mouse wrote:
I dimly remember that the old rcons code draws at least the cursor
and maybe all text by software and uses the blitter only for
scrolling and rectangle fills.
Depends. Looking at the 3.1 code, I see CG6_BLIT_CURSOR, which if
turned on seems to do the cursor with the blitter.
I added that option years ago when I found out that it locked up one
of my CG6. For some reason the same code works fine with wscons.
As I recall, most of the usability gain from cg6 acceleration came
scrolling. There is some font-draw support in the hardware, but I
suspect it's not that much faster than software font-draw.
It's several orders of magnitude faster ( I implemented it for
NetBSD's own xf86-video-suncg6, it beats the pants off most
contemporary and many newer chips. x11perf -ftext yields more than
400000 characters per second on a TGX )
But as you said, scrolling is by far the most noticeable acceleration
feature in the kernel driver.
When using the blitter for all operations we can queue up character
drawing too instead of having to wait for the blitter to finish which
is the main reason why I added it to most of my drivers. Less CPU time
Perhaps the next step is shutting [RASTERCONSOLE] off, and seeing
if the problem persists.
That would be an interesting datapoint. With no wscons and no
REASTERCONSOLE, console display _should_ go through the PROM
callbacks, AIUI; [...]
I'm pretty sure the PROM drawing routines for the cg6 use the blitter
for at least a few things.
Yes. Scrolls, at the very least; it scrolls too fast to be anything
Exactly what I thought - see a cg14 for comparison, then add sbus's
However, don't callouts to the ROM code run with a bunch of stuff
disabled? That should help some....
I think we disable at least interrupts when calling the PROM.
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