Subject: Re: powering down pcmcia/cardbus slots
To: Steven M. Bellovin <smb@cs.columbia.edu>
From: Garrett D'Amore <garrett_damore@tadpole.com>
List: tech-kern
Date: 02/16/2006 08:24:32
You are saying PCMCIA, but your dump indicates USB. Am I missing something?

-- Garrett

Steven M. Bellovin wrote:
> I have a card that, on removal, sometimes crashes my machine.  The card 
> is an EVDO modem:
>
> ohci0 at cardbus0 function 0: NEC USB Host Controller (rev. 0x43)
> ohci0: interrupting at 11
> ohci0: OHCI version 1.0
> usb4 at ohci0: USB revision 1.0
> uhub4 at usb4
> uhub4: NEC OHCI root hub, class 9/0, rev 1.00/1.00, addr 1
> uhub4: 1 port with 1 removable, self powered
> ohci1 at cardbus0 function 1: NEC USB Host Controller (rev. 0x43)
> ohci1: interrupting at 11
> ohci1: OHCI version 1.0
> usb5 at ohci1: USB revision 1.0
> uhub5 at usb5
> uhub5: NEC OHCI root hub, class 9/0, rev 1.00/1.00, addr 1
> uhub5: 1 port with 1 removable, self powered
> umodem0 at uhub4 port 1 configuration 1 interface 0
> umodem0: Curitel Communications, Inc. Curitel Communications, Inc., rev 1.10/0.00, addr 2, iclass 2/2
> umodem0: data interface 1, has CM over data, has break
> umodem0: status change notification available
> ucom0 at umodem0
>
> I run ppp over it.  (That has its own set of problems, but they're not 
> the point of this note.)
>
> Anyway -- I of course kill pppd before removing the cards.  With 
> moderate frequency, though -- say, about 10% of the time -- when I 
> remove the card the laptop reboots.  As best I can tell, it's not going 
> into ddb nor panicking, but since I've never seen any messages I can't 
> be certain.  (Recently, I've started killing my Console window and 
> switching to screen 1 before removing the card, to see if anything 
> shows up.)  There definitely haven't been any dumps.  The question, 
> then, is what would cause a machine to spontaneously reboot.
>
> My current working hypothesis is that it's a power glitch.  I'd like to 
> be able to power down the slot before removing the card.  If necessary, 
> I'm willing to power it back up manually when inserting a card, though 
> it would nicer if I didn't have to worry about that.
>
> So -- how can this best be done?  (And does anyone have any better 
> hypotheses about why the machine crashes?)
>
> 		--Steven M. Bellovin, http://www.cs.columbia.edu/~smb
>
>   


-- 
Garrett D'Amore, Principal Software Engineer
Tadpole Computer / Computing Technologies Division,
General Dynamics C4 Systems
http://www.tadpolecomputer.com/
Phone: 951 325-2134  Fax: 951 325-2191