Date: Thu, 6 Apr 1995 03:38:48 +1000 From: Bruce Evans <bde@zeta.org.au> To: peter@bonkers.taronga.com, phk@ref.tfs.com Cc: freebsd-hackers@freefall.cdrom.com, uhclem@nemesis.lonestar.org Subject: Re: Suggestion on slow probing devices Message-ID: <199504051738.DAA26590@godzilla.zeta.org.au>
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>> > The solution was to create two probing passes. The system would >> > effectively call each devices' probe routine twice. >> >> How about generalizing it? If there's a big delay, have the probe return a >> flag saying "more work to do, call me again after you've asked everyone else". >> That way you could handle multi-stage delays, like with SCSI. >I'd say the right thing to do would be to get the timer flying and make >a "HW-probe-attach" process... lkm'ed drivers will make this both easier and harder. Easier because they will have an process context to sleep on so they won't need to call DELAY() for long delays. Harder because they must leave the device in a safe state before sleeping and because they must not call DELAY() for delays longer than are acceptable in normal operation (perhaps 100usec max). Bruce
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