Date: Thu, 22 Jul 1999 18:39:10 +0000 (GMT) From: Terry Lambert <tlambert@primenet.com> To: nate@mt.sri.com (Nate Williams) Cc: tlambert@primenet.com, scheper@beast.toad.net, freebsd-smp@FreeBSD.ORG Subject: Re: SMP + XDM = keyboard lockup Message-ID: <199907221839.LAA10550@usr05.primenet.com> In-Reply-To: <199907221812.MAA02907@mt.sri.com> from "Nate Williams" at Jul 22, 99 12:12:02 pm
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> > The xdm program, among other things, starts X. > > > > I believe the issue is one CPU running X doing inb/outb's while > > the other CPU is in the kernel -- doing the same. > > Why would the other CPU doing the same inb/outb's as X? By the time > init is run, the kernel is done 'setting up' the kernel. It wouldn't be. It would merely be trying to latch different addresses on the I/O bus and/or write data to the previously latched address, at the same time. Basically, user space code should keep its cold, wet nose out of the kernels crotch. I believe the issue is the system is still starting up, and thus has the kernel poking at things. You could guess that the init and the X server might be running on different CPU's, but then you would expect the /etc/ttys file based xdm startup to work. This jibes with his statement that manually starting the xdm from a root shell prompt on a relatively quiescent system "works". It is likely that it "works" only because there is not simultaneous activity. If I am correct, I suspect that on an active SMP system, console switching in and out of X would result in similar lockups, so this should be verifiable. Since he appears to have a way in, other than the console, he should: 1) Cause the lockup 2) Go in and do a 'ps' to see if conflicting processes are running 3) Force a console switch via escape sequence to a console vty not currently in use. This should result in the X server disengaging, and the input devices being detached and reattached to the new vty, if the problem is merely a race. Also, if both terminals are reading input, as has been posited, a ctrl-alt-F2 should still result in a console switch, regardless of who takes the keypress event (ctrl and alt are modifiers, so only the F2 keycode should be relevent). Terry Lambert terry@lambert.org --- Any opinions in this posting are my own and not those of my present or previous employers. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-smp" in the body of the message
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