Subject: Re: sudden detach
To: Garrett D'Amore <>
From: John Nemeth <>
List: tech-kern
Date: 07/12/2006 01:45:08
On Dec 1,  7:38am, "Garrett D'Amore" wrote:
} David Young wrote:
} > On Tue, Jul 04, 2006 at 03:23:02PM +0200, Jachym Holecek wrote:
} >   
} >> If we can agree to require user intervention before removing hotplug
} >> devices (which is what Windows XP does, not sure about other systems),
} >> then we "should" get rid of ca_activate (as we know it now, anyway).
} >> There was a short thread on this recently, the argument for keeping
} >> them was exactly "we need a quick deactivation from hardintr when
} >> we get a device-gone interrupt".
} >
} > I have always considered it a bug in Windows XP that the user has to
} > intervene before a device can be removed.  I thought that both USB and
} > Cardbus were designed to make a sudden detach possible?  In principle,
} > can't a carefully written driver survive a sudden detach?
} In principle this is true for USB, and it _may_ be true for Cardbus. 
} But the reality is that cardbus drivers generally share code with PCI
} (for most OS' they use the same driver entirely, although for some
} reason NetBSD has a separate Cardbus support apart from PCI) and those

     Many of the Cardbus "drivers" are just bus attachment frontends
which use common chipset backends found in sys/dev/ic.

} drivers are generally _not_ hotplug safe.

     What about PCI Hot-Plug?  Sounds to me that if drivers can't
handle sudden detach now, they will need to do so in the future.

}-- End of excerpt from "Garrett D'Amore"