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looking for testers of new console

From: Marcus Brinkmann
Subject: looking for testers of new console
Date: Thu, 19 Sep 2002 04:08:04 +0200
User-agent: Mutt/1.4i


the new Hurd console is now part of the source and of the latest
Debian package.  This is the time to let as many people as possible
test it to get feedback and bug reports, before the development is

Please let me know how it works for you.  This is only tested on two
VGA cards so far, and I would expect some problems with other VGA cards.
Also, let me know if you found a particular feature too cumbersome to
use or missing, or if you had problems following these descriptions.

But please be aware that this is the very first version of the console
that gets wider use.  I did a lot of testing on my own system, and am
quite confident of the stability and bug-freeness of the code (which
doesn't mean that it never crashes or is completely bug free, it just
means that all the usual features should work without any serious
problems).  But as with all new software, there are likely some bugs
you will encounter that might make your life harder, or even lead to
data loss.

I am aware that the installation is not as simple as it could be.  But
we are not making this code the default unless we are more confident
about its stability and relatively feature completeness.

See at the end of this mail for some known limitations and problems.

Please note that I have just uploaded the Hurd package.  As usual, it can
take a day or two to reach the archive and your mirror.

What is the new console?

The new Hurd console features:

* A console server which provides a number of virtual consoles to term
  servers, with a full set of terminal capabilities.

  The console server supports any encoding supported by iconv, but
  uses Unicode internally.  The default encoding is ISO8859-1, another
  useful variant is UTF-8.

  The console server provides an arbitrary number of virtual consoles
  (numbered starting from 1, but the numbers don't need to be
  consecutive), which are created dynamically.  A virtual console is
  not automatically displayed, for this you need a console client
  program which attaches to the virtual console you want to use.

  You can attach any number of console clients to the same virtual
  console, and detach them at any time.

  The console server provides a scrollback buffer for each virtual
  console.  Currently, this is about one and a half screen full in
  addition to the screen.  This should be configurable, of course, but
  isn't right now.

* libcons, a library that makes it easy to write console clients that
  attach to the console server.  The client interface of the server is
  quite complicated, because it is based on shared memory and
  broadcasts the data to potentially many clients without blocking.
  It also includes a notification scheme so that clients remain idle
  when there is no console activity.  This saves cpu power (compared to
  the alternative which would be polling).

* The default console client, which you will normally use to use a
  virtual console in a console server.  Rather than writing many
  similar console client programs, I decided to write only one
  initially and make it extensible via dynamically loaded modules
  called "drivers".

  The console client uses libcons, of course.  There are a number of
  drivers that exists already:

  * The ncursesw driver.  You can use this if you log in from a remote
  unicode-capable console to attach to the local console server and
  use virtual console over the telnet/ssh session or similar.  The
  ncursesw driver contains an output, input and bell driver
  components, so it is the only driver you need to get full access.

  * The vga driver.  The VGA driver can be used locally to display a
  virtual console on a VGA card device.  This driver provides a number
  of exciting features, and all of them are available in the fast text mode,
  and do not require a graphical framebuffer:

    * BDF font support.  Load any BDF font with a Unicode encoding and
    a size from 8x13 up to 9x15 (recommended).

    * Dynamic glyph allocation.  You can use up to 512 glyphs at any time.
    This means you can display cyrillic, greek, english runes, thai, etc
    often at the same time, up to 512 different glyphs on the screen
    in parallel.  The 512 is not a fixed set, they are chosen automatically
    out of the font you have loaded.  This means that we only need one
    font for all users, regardless of the locale.

    * Dynamic color allocation.  Because the above 512 glyph modus is
    only available with a reduced amount of colors, you can use only
    up to 8 different colors, but which of the 16 colors are available
    is chosen dynamically based on the colors actually used.

    Note: There is an alternative mode with up to 256 different glyphs
    at the same time and full 16 colors, for those who need many
    colors in their applications.

    * Support for multiple fonts at the same time.  The VGA driver
    supports italic and real bold (not bright color) mode.  This will
    hopefully be used in emacs font lock mode and other applications.

  * The pc_kbd driver.  This is a hack for a PC eyboard with an
  american keymap.  We all want configurable keyboard layouts of
  course, but I had to set priorities, and extracting xkb (so we can
  reuse the X keymaps) is on the TODO list.  For now, this driver with
  a fixed US keymap is available for immediate use.  Although it is
  only considered to be a temporary solution, it provides all features
  you need (except changing the keymap):

    * All keys of a standard 102(?) keys keyboard, including Ctrl, LeftAlt,
    RightAlt, CapsLock, NumLock, Keypad, cursor block, function keys
    are supported and have a sensible default value.

    * LeftAlt + Function key N switches the virtual console N.

    * LeftAlt + ArrowRight or ArrowLeft switches to previous or next
    virtual console.

    * RightShift + PageUp or PageDown scrolls back or forward in the
    scrollback buffer by half pages.

    * LeftAlt + ArrowUp or ArrowDown scroll back or forward one line.

    * LeftCtrl + LeftAlt + Backspace terminates the console client,
    and reverts the VGA card etc to its original state.

    * RightAlt + Keypad enables you to directly enter unicode
    characters in hexadecimal numbers.  0-9 have their standard
    meaning, and NumLock is 0xa, Keypad / is 0xb, * is 0xc, - is 0xd,
    + is 0xe and the enter key at the lower right of the keypad is 0xf.
    Up to four digits are memorized, if you type more, the earlier
    ones are forgotten.  This allows to cover up typing mistakes.

    For example: AltGr + (Keypad 4, Keypad 1) = 0x41 = 'A'.
                 AltGr + (Keypad 2, 6, 3, NumLock) = 0x263a = smiley.

    You can get unicode tables from www.unicode.org.

  * The generic_speaker driver supports the speaker commonly found in
  PCs and other computers.  It is good enough for a simple bell tone or
  a small melody.  I have several default bell styles implemented, but
  currently there is no configuration option to access them at run
  time, sorry!  Load this module to make the console beep on ^G.

How do I install the new Hurd console?

You either need the latest .deb of the Hurd, version 20020918-1 or
later, or you need current CVS sources and compile them yourself.

Then, the console server is in /hurd/console, the client in
/bin/console.  The installation is painless.

First, make some device files:

# cd /dev
# ./MAKEDEV vcs tty1 tty2 tty3 tty4 tty5 tty6

The above six ttys are only suggestions.  You might want to give or
take a few, depending on your needs.

You need the terminal description.  This is not yet in the ncurses
package, because I am not finished yet.  But you can download it from


Please add it with

# tic -x hurd.ti

Then you should add the terminals to ttys, so you get a login session
on them at boot time.  Edit the file /etc/ttys, and add the following
lines (or similar if you made more/less ttys):

tty1    "/libexec/getty 38400"          hurd            on      secure trusted 
tty2    "/libexec/getty 38400"          hurd            on      secure trusted 
tty3    "/libexec/getty 38400"          hurd            on      secure trusted 
tty4    "/libexec/getty 38400"          hurd            on      secure trusted 
tty5    "/libexec/getty 38400"          hurd            on      secure trusted 
tty6    "/libexec/getty 38400"          hurd            on      secure trusted 

This is all.  If you now reboot, you will get six virtual consoles
with a login prompt on each.  But of course, the console client is not
started automatically yet, so you don't see them.  Login at the normal
system console, and try to attach to the console server, either with
the ncurses driver or with the vga/pc_kbd driver:

# console -d ncursesw /dev/vts


# console -d vga -d pc_kbd -d generic_speaker /dev/vts

That should work.  The ncursesw driver supports console switching via
C-w C-1 (or 2, 3, ...) and you can exit it with C-w x.  But I
recommend the use of the vga client on the local console.

The virtual consoles you are now running on are providing an ISO8859-1
environment (also known as latin1), which is good enough for the USA
and some countries in Europe.  If you require a different encoding for
your locale (like, let's say, ISO8859-2), you can specify this as an
argument to the console server.  I am sorry to say that fsysopts
doesn't do the trick yet, so you have to set the option with settrans
-fg, which will _terminate all your login sessions and restart the
console server_.

To do this, _first_ exit the client.  It will get disconnected anyway
(and doesn't attempt to reconnnect yet in such a case).  Then do a

# settrans -fg /dev/vcs /hurd/console --encoding=ISO8859-2


# settrans -fg /dev/vcs /hurd/console --encoding=UTF-8

or similar.  A list of supported locales is not easily available, but
you can poke into /share/i18n/SUPPORTED to get an idea what is
expected for your locale, and you can also check out
/share/i18n/charmaps.  Theoretically all of these encodings are
"supported".  In the file SUPPORTED, you see the locale (what you
should export in the LANG environment variable, and enable in
/etc/locale.gen) and the corresponding encoding.

If you actually try this, you will notice two problems:

1. You can not enter the letters in your locale, because the keyboard
doesn't have the right layout.  See above.  Keyboard maps come later.
For now, you have to help yourself with the direct input with
RightAlt.  Maybe I will put a simple compose key feature in the pc_kbd
driver, so that some western locales can be used more easily.

2. If you bother to look up the unicode hex code and enter it with
AltGr, the font can not display it!  If you are using the ncursesw
driver, do you use it while you are logged in from a working UTF-8
terminal?  If not, then this is your problem.  An ncurses driver for
non-UTF-8 terminals is on the TODO list.  But if you use the VGA
driver, you need to load a different font.

This is because by default, the vga driver just reads the VGA card
memory and takes the font that is stored there.  This font has a
limited characterset (256 characters, many graphical symbols among
that), so you won't get more than a few western characters with that.

Unicode support

But you want it all.  You want to read Middle Old English.  You want
to read Thai.  Your Korean spam.  Georgian script.  Hebrew.  And you
can have it.

You need a Unicode font.  There are good ones providd by Markus Kuhn,
the UCS fonts.  Get them here:


(See also the web page at http://www.cl.cam.ac.uk/~mgk25/ucs-fonts.html).

Now, load the font by providing it with the --font option to the vga
driver.  I suggest only the 8x13 and the 9x15 fonts, but feel free to
try others, too.  Note that the VGA text mode can not really display 9
pixel wide characters.  But as most characters have the ninth column
empty, and the VGA text mode can display an empty column between two
adjacant character cells, this trick allows us to display most of the
9x15 font correctly.  So you won't notice a difference until you come
to very broad characters or special symbols, where you will see that
the last column is cut off.  (BTW, I wrote the dynafont code carefully
to still support horizontal line graphic characters properly in 9
pixel wide fonts.  This is done by exploiting some special modes in
the VGA hardware.  This is why in 512 (256) glyph mode and 9 pixel
wide fonts, you are limited to 448 (224) normal characters: 64 (32)
slots are reserved for the horizontal line graphic characters so they
are drawn continuously.)

So, try the following:

# console -d vga --font 8x13.bdf -d pc_kbd -d generic_speaker /dev/vts


# console -d vga --font 9x15.bdf -d pc_kbd -d generic_speaker /dev/vts

If you are satisfied, copy your default font to
/lib/hurd/fonts/vga-system.bdf, where it will be picked up
automatically in favor to the graphic card's font.

More about fonts

While we are talking about fonts, try also the 8x13O font with
--font-italic and 8x13B or 9x15B font with --font-bold.  You can save
them in /lib/hurd/fonts/vga-system-bold.bdf and
/lib/hurd/fonts/vga-system-italic.bdf, too.

To activate those fonts on your virtual console, try the following:

# echo `tput sitm`Hello slanted world.`tput ritm`


# echo `tput gsbom`Hello bold world.`tput grbom`

I hope you like what you see.  Imagine this in emacs font-lock mode.

Unicode, finally

There are a few more steps necessary to make your Unicode environment

Install the locales package.  The current version does want a newer
glibc than we have in the archive, but this can be overridden with the
--force-depends option to dpkg.  The old glibc is good enough.

Add a Unicode locale to /etc/locale.gen, and generate the locale
information for that!  For example, I am living in Germany, and
normally use de_DE with the encoding ISO8859-1.  My Unicode locale is
de_DE.UTF-8, so I am adding that to /etc/locale.gen:

de_DE.UTF-8 UTF-8

and rerun locale-gen:

# locale-gen

See also /share/i18n/SUPPORTED.  You can also do this more conveniently with

# dpkg-reconfigure locales

Once you generated this, make it your default locale:

# export LANG=de_DE.UTF-8

If you have also loaded the unicode font above, you are set up.  Try
for example to view the examples/ files in the ucs-fonts package with

# less fonts/examples/UTF_8-demo.txt

You should see most of that file with the 9x15 font (a bit less with
the 8x13 font).

You should be able to do the above process with other encodings than
UTF-8.  But you should _always_ use a Unicode font, because the
console client uses Unicode internally fo everything.

Application specific notes

If you enter unicode characters at the shell, libreadline loses track
of the number of characters displayed (it is not aware of multi-byte
encodings like UTF-8).  This is fixed in readline 4.3 (which is not
yet in Debian).

If you use mutt, install mutt-utf8.  For lynx, edit /etc/lynx.cfg,
making sure that CHARACTER_SET is set to utf-8.

If you use other applications, try to search with google for
"application-name utf8" or "application-name unicode".  Often you find
what you need.  The issues are the same for the GNU/Hurd and GNU/Linux
systems, so most of the information can be shared, except how to setup
the system console to support Unicode, of course.

Known problems and important missing features

Squeezed at the end so nobody sees it ;)

1. console server: lacks configuration option for scrollback buffer
   length.  Is probably too lax in permission checking.  Does not
   implement settable tab stops.  Does not allow to change encoding at
   run time.  Does not allow any other screen size but 80x25.

   Combining characters are not supported.

2. libcons/console-client: If you have one virtual console active, and
   another one receives a bell character, you don't hear the bell.
   This is because only the active virtual console is watched for
   anything interesting to happen.  I think that is ok, but you might be
   surprised if you are used to how it works on GNU/Linux.

   Copy & Paste not supported.
3. vga driver: Does not have configuration option for
   256glyphs/16colors mode.  Does not recalculate the mode lines if
   the font height is changed.  This makes font heights below 13 or
   over 16 infeasible.

   Should support other text modes (integrate svgatextmode?)

4. generic_speaker driver: No option to set bell style.

5. pc_kbd driver: No keyboard layout but US supported!  Maybe in some
   cases left/right shift/ctrl/alt is allowed where both left and right
   should be allowed.  Doesn't support keyboard LEDs.

6. ncursesw driver: Doesn't work properly on other terminals but UTF-8.
   Should not use C-w, this should be configurable.  Does not support
   use of scroll back buffer.

7. Other programs: Readline doesn't support multibyte encodings (4.2
   and earlier).  term doesn't either (all versions).  

`Rhubarb is no Egyptian god.' GNU      http://www.gnu.org    marcus@gnu.org
Marcus Brinkmann              The Hurd http://www.gnu.org/software/hurd/

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