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Path: euryale.cc.adfa.oz.au!newshost.anu.edu.au!harbinger.cc.monash.edu.au!news.mira.net.au!vic.news.telstra.net!act.news.telstra.net!psgrain!newsfeed.internetmci.com!tank.news.pipex.net!pipex!news.mathworks.com!fu-berlin.de!zib-berlin.de!news.tu-chemnitz.de!irz401!uriah.heep!news From: j@uriah.heep.sax.de (J Wunsch) Newsgroups: comp.unix.bsd.freebsd.misc Subject: Re: Probably VT switching bug (2.1-R) Date: 13 Apr 1996 01:06:12 GMT Organization: Private BSD site, Dresden Lines: 31 Message-ID: <4kmum4$f8c@uriah.heep.sax.de> References: <316E5601.41C67EA6@rwwa.com> Reply-To: joerg_wunsch@uriah.heep.sax.de (Joerg Wunsch) NNTP-Posting-Host: localhost.heep.sax.de Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8bit X-Newsreader: knews 0.9.3 Robert Withrow <witr@rwwa.com> writes: > I've noticed an annoying problem with both Xfree and > Xinside, related to VT switching. If I am unlucky and > pick exactly the wrong time to switch VTs, I can get > the system into a state where it henceforth refuses > to switch VTs forevermore. The VT switching approach is rather icky when it comes to things like X11 that have been moved much of the work that would have belonged into the kernel out to userland. The result is that the intervention of a user process (the Xserver) is required in order to complete a VT switch. This is accomplished by a mishmash of ioctl's and signals, forming a simple handshake. If you disturb this handshake in an unlucky moment, you're totally stuck. The first VT switch has been half-complete (e.g., the switch from the text VT to the graphics VT where your xdm tried to start the Xserver), when the hotkey for the second keyswitch arrived. So the first VT switch eventually never completes, but the graphics VT is already blocked, and the second VT switch will never happen, since the process that has just been registering itself as the ``owner'' of the graphics VT didn't release it again. Sad, but the horrible truth. -- cheers, J"org joerg_wunsch@uriah.heep.sax.de -- http://www.sax.de/~joerg/ -- NIC: JW11-RIPE Never trust an operating system you don't have sources for. ;-)