Re: Experiences with FreeBSD 9.0-BETA2

From: Brett Glass <brett_at_lariat.net>
Date: Fri, 07 Oct 2011 07:40:08 -0600
Ed:

The patch is an improvement. Not assuming that tabs blank the underlying
cells is definitely a help. But it does not fix all of the artifacts.

It might be a good idea to review the "xterm" termcap entry, capability
by capability, to make sure that syscons conforms to each one. As the
author of a very exacting vt100 emulator (I wrote Borland's "Turbo Terminal"
back in the 80s), I know just how quirky, poorly documented, and buggy some
terminals can be. I had to emulate every strange behavior and bug in the
vt100 without access to the source code that the embedded CPU was running.
In general, the behaviors that cause the most problems are wrapping and
unwrapping text, writing past the edges of the screen, positioning near
the edges of the screen, and manipulating the top and bottom lines. The
vt100, for example, would not scroll when you wrote the last character on
a line, but would then scroll if you entered one character after that
without executing a command that repositioned the cursor. It would also
ignore linefeeds after automatic scrolling (due to DEC's convention that
text files have both a CR and an LF at the end of each line rather than
just an LF as in UNIX). If you'd like, I can try to come up to speed on
the code and help to debug, but I do not use X and so have no experience
with its default terminal emulator; I'd have to study that as well.

--Brett Glass

At 06:25 AM 10/7/2011, Ed Schouten wrote:

>* Ed Schouten <ed_at_80386.nl>, 20111007 13:02:
> > It should be xterm, since syscons now uses an xterm-style terminal
> > emulator. I have never used jove before, so what should I do to
> > reproduce this?
>
>After some tinkering, I think I know why it breaks. I thought that
>when xterm processes a tab, it blanks the underlying cells. This doesn't
>seem to be the case, so I've fixed that in r226099.
>
>Would it be possible for you to test HEAD r226099 or apply this patch to
>your source tree?
>
> 
>http://svnweb.freebsd.org/base/head/sys/teken/teken_subr.h?r1=223574&r2=226099&view=patch
>
>If so, there's a fair chance I can get it squeezed into 9.0. Thanks!
>
>--
>  Ed Schouten <ed_at_80386.nl>
>  WWW: http://80386.nl/
>
Received on Fri Oct 07 2011 - 11:40:10 UTC

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