Messages in this thread |  | | Date | Wed, 29 Jan 2003 17:09:14 -0500 (EST) | From | Scott Murray <> | Subject | RE: [Pcihpd-discuss] [RFC] Enhance CPCI Hot Swap driver |
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On Wed, 29 Jan 2003, Ed Vance wrote:
> On Tue, January 28, 2003 at 12:40 AM, Rusty Lynch wrote: > > > > On Tue, 2003-01-28 at 23:50, Stanley Wang wrote: > > > Hi, Scott, > > > After reading your CPCI Hot Swap support codes, I have a suggestion > > > to enhance it: > > > How about to make it be full hot swap compliant? > > > I mean we could also do some works like "disable_slot" when > > we receive > > > the #ENUM & EXT signal. Hence the user could yank the hot > > swap board > > > without issuing command on the console. > > > How do you think about it? > > > > > > > How does this behavior translate to "full hot swap > > compliant"? I assume > > you are talking about wording from PICMG 2.16, which in my opinion > > describes the full software stack, not just the driver. Any kind of > > full CPCI solution would have all the user space components to > > coordinate disabling a slot before the operator physically yanks the > > board (and therefore behave as PICMG specifies). I'm not so sure the > > driver knows enough to make a policy decision on what to do when an > > operator bypasses the world and just yanks a board out with > > no warning. > > How is this functionally different from ejecting a PCMCIA card in use? Is > the driver obligated to do more than prevent a system crash and present > errors to user level until the last close?
cPCI hotswap as defined in the PICMG 2.1 specification is a different beast from PCMCIA because it was purposely defined to give software a chance to do something before the device disappears. The specification even goes so far as to say that the system is in an undefined state if a device is yanked without waiting for the system software indicating it is safe to do so. In reality, handling someone yanking a board is indeed desireable, although it seems unlikely that the vast array of PCI device drivers will ever get updated to handle it.
Scott
-- Scott Murray SOMA Networks, Inc. Toronto, Ontario e-mail: scottm@somanetworks.com
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