Re: [Xen-users] xen console dimensions

[Atom2 <ariel.atom2@xxxxxxxxxx>]

Am 24.06.14 16:02, schrieb Austin S Hemmelgarn:
> On 2014-06-24 09:30, Ian Campbell wrote:
> > On Tue, 2014-06-24 at 09:21 -0400, Phillip Susi wrote:
> > > On 6/24/2014 8:39 AM, Ian Campbell wrote:
> > > > On Tue, 2014-06-24 at 08:36 -0400, Austin S Hemmelgarn wrote:
> > > > > I've checked, and it does appear that running resize works to
> > > > > correct things on Linux, I don't know about NetBSD however (I
> > > > > don't have any NetBSD guests to test with right now).  The issue
> > > > > is that COLUMNS and LINES aren't getting set, which makes things
> > > > > assume 80x25 terminal geometry (for compatibility reasons).
> > > > Thanks for checking. Philip does that fix it for you too?
> > > Yes, manually setting it with stty allows for proper operation; it
> > > just seems that this information should be automatically passed to the
> > > guest ( via xenstore? ) by xenconsole, and then hvc driver in the
> > > guest should pass it to the tty core.  Also updating it in response to
> > > SIGWINCH when you resize the terminal.
> > I'm pretty certain you don't get that level of functionality with a
> > normal serial port, but patches welcome ;-0
> >
> > Ian.
> That's generally true, although once you reach userspace, either getty
> or init usually set COLUMNS and LINES correctly, I have no idea how they
> determine the correct values.  There is an ANSI escape sequence that is
> supposed to return hardware/emulator identification, and I think most
> VTEs return their geometry through this.  I think I remember reading
> somewhere about a non-ANSI escape sequence that returned just the
> geometry, I think it was for the vt100 series (and by extension, Linux
> console, GNU screen, and xterm compatibles).  IIRC, on Solaris they get
> set based on the terminal type that gets passed to getty (or at least on
> old Solaris systems)
I was annoyed by this a long time ago and have (back some time) found a 
workable solution - at least for me. After a lengthy digging excercise 
through the internet using google I found a small piece of C code 
somewhere (I can't remember where) which seemd to be what I am after. I 
downloaded it and compiled it. I called the binary resize, put it under 
my /usr/local/bin and created an alias for my bash which reads
        alias cd='resize ; cd'
In essence this means it gets fired whenever I issue a cd command. It is 
quick, so there is no noticeable delay and it resizes the window to 
whatever the ssh terminal emulator (I use putty) is set to at that time.
You could use every command for the alias, but the cd command is one 
that I frequently use. The alias sequence therefore updates the window 
size not constantly, but with a reasonable frequency.
Over and above this I have included the following sequence in the global 
/etc/bash/bashrc file so it gets fired for every login process and sets 
the size correctly at login:
        if [[ -z "$STY" ]]; then
                /usr/local/bin/resize   # set correct terminal size
        fi

Clearly this approach is not fool-proof and it can miss changes from 
time to time (mostly notable in vi, but then getting out and using cd 
[or even just start resize] immediately rectifies the situation).
I have attached the source code of this program in the hope that the 
logic used could somehow be incorporated into XEN to make things 
automatic. It is only 200 odd lines of code including around 50 lines of 
headers/comments and around 20 lines of #include statements - so not 
very complicated for someone who understands terminal emulation.
But I have to admit I am with Ian here: Terminal emulation is a bit of a 
mystery to me as well ...
Regards Atom2

_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxx
http://lists.xen.org/xen-users