Re: [gdm-list] GDM - gdmdynamic and Sun Ray support

[Mike Oliver <Mike Oliver Sun COM>]

Brian Cameron wrote:
> A Sun Ray display is basically a display that does not support
> virtual-terminal style switching.  For utmp/audit/etc. purposes
> it uses a pseudo device /dev/dtlocal as the device.

Sun Ray doesn't know or care about /dev/dtlocal.

The /dev/dtlocal path is simply a convention shared between the
display manager and the consumers of utmpx/wtmpx.  The convention
that "dtlocal" is placed into the ut_line member of the utmp
record for a locally-managed X display was, AFAIK, introduced by
the CDE display manager 'dtlogin'.  Remote X logins get similar
treatment except that the magic name in that case is "dtremote".
The X display name is placed in the record's ut_host member.

This serves two purposes.  Firstly, because /dev/dtlocal and
/dev/dtremote exist (albeit only as symlinks to /dev/null) it
prevents naive utmpx/wtmpx consumers from blowing up when their
stat() of /dev/<contents-of-ut_line> fails.  Secondly it allows
utmpx/wtmpx consumers who are aware of this convention (eg 'last'
on Solaris) to get sane results for X logins whose display names
are too long to fit into the ut_line field but will fit into the
ut_host field.  (This is more of an issue for remote logins but
it can affect local displays too.)

GDM-on-Solaris follows the same convention for the same reasons,
completely independently of any consideration of the kind of
frame buffer that underlies the X server.

'dtlogin' also gives special treatment to an X server that is
designated as being "on-console", because some utmpx consumers
want to recognise that case.  I've lost track of whether GDM
provides the same special treatment.

Mike.
--
mike oliver sun com