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Date: Thu, 6 Mar 2014 02:02:46 +1100 (EST)
From: Bruce Evans <brde@optusnet.com.au>
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To: Bruce Evans <brde@optusnet.com.au>
Subject: Re: newcons fb driver
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Cc: Justin Hibbits <jhibbits@freebsd.org>,
 Poul-Henning Kamp <phk@phk.freebsd.dk>, freebsd-arch@freebsd.org
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On Thu, 6 Mar 2014, Bruce Evans wrote:

> On Tue, 4 Mar 2014, Justin Hibbits wrote:
>> Without some kind of optimization, newcons on powerpc is unacceptably slow.
>
> How slow is that exactly?  If the frame buffer speed is 50MB/S, then
> 16x8 characters with 256 colors can be written at 390K/S.  This is
> acceptable.  If the frame buffer is much slower than that, then it is
> too slow, at least without hardware scrolling.

I forgot to mention that u$ doesn't solve this problem in WinXP.  The
speed is not too bad in normal mode (only about 30 times slower than
syscons - the scrolling speed is 30000 lines/second instead of 1000000).
But in safe mode, a simple graphics driver is used and it is horribly
slow.  Safe mode with command prompt gives an MSDOS prompt in a
maximized terminal window, so the problem is very noticeable (the
scrolling speed is 4 lines per second = 12 seconds per screenful).
Apparently normal mode uses acceleration to be not very slow, but safe
mode is too simple to do that.  The FreeBSD console driver needs to
be even simpler so that it works as a low level console.

Bruce