Date: Mon, 03 Jul 2000 10:52:26 -0600 From: Warner Losh <imp@village.org> To: Poul-Henning Kamp <phk@critter.freebsd.dk> Cc: Garrett Wollman <wollman@khavrinen.lcs.mit.edu>, Nick Hibma <n_hibma@calcaphon.com>, cvs-committers@FreeBSD.org, cvs-all@FreeBSD.org Subject: Re: cvs commit: src/sys/sys bus.h bus_private.h src/sys/kern subr_bus.c Message-ID: <200007031652.KAA23743@harmony.village.org> In-Reply-To: Your message of "Mon, 03 Jul 2000 18:40:23 %2B0200." <7096.962642423@critter.freebsd.dk> References: <7096.962642423@critter.freebsd.dk>
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In message <7096.962642423@critter.freebsd.dk> Poul-Henning Kamp writes: : It's a hard call, and I'm not sure it is the best idea to decide this : on a global basis: ie, the model we use for ethernets and disks may : be radically different. : : In a way I like the way Windows did this, by having a set of : configurations, ie: undocked, docked, undocked + pccard etc etc : : In fact the best idea may be to make this a per device variable: : : "if your hardware disappears, stay around" : or : "if your hardware disappears, go away" When would you want it to stay around? What would you do with access while the hardware was gone? How do you know if the same card was inserted, or one that is the same enough? How do you know if the hardware is even connected to the same thing it was when it was plugged in before? What do you do in these situations? If I unplug a network card, you'd think it was fairly simple to just shove it back it and be where you were before. However, the NIC may have changed (if I have two identical cards), which means that IPv6 stuff needs to do special things. You have to go through a configuration process again to ensure that things are working right. What advantage is gained by having the logical device stick around in the interrum? If I plug a flash card in, then how do the answers changed? With a flash card or any kind of disk controller, I want the answer to be "it goes away always". With a modem, there's no use having the device there if I can't open and interact with it. At the very least the device should return ENXIO on opens to the device. There's no state information that would survive the removal and insertion in the hardware, nor is there configuration information in the softc that wouldn't be easy to reconfigure on reinsertion. It is an ugly problem that I'm not sure buys you much. Warner To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe cvs-all" in the body of the message
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