Date: Wed, 30 Sep 1998 14:05:57 -0600 (MDT) From: "Kenneth D. Merry" <ken@plutotech.com> To: karl@Denninger.Net (Karl Denninger) Cc: tom@uniserve.com, dnelson@emsphone.com, bright@hotjobs.com, current@FreeBSD.ORG Subject: Re: Long IDE probes? Message-ID: <199809302005.OAA01044@panzer.plutotech.com> In-Reply-To: <19980930130459.A4393@Denninger.Net> from Karl Denninger at "Sep 30, 98 01:04:59 pm"
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Karl Denninger wrote... > On Wed, Sep 30, 1998 at 11:00:45AM -0700, Tom wrote: > > Hehe... that is pretty funny. I have a system here that will refuse to > > start after a power-start because the BIOS can't find the boot disk > > because it hasn't come ready yet. It is a SCSI disk, and the SCSI adaptor > > has probed it. I need to warm-boot the system at the "Please insert boot > > disk" message, and then it will boot from the hd. > > The point is that once the BIOS has found the disk and *booted from it*, you > then *KNOW* that it is available and online (duh!). Second, the delay on > the SCSI side is only for the disk to respond to an inquiry - as long as > that happens the rest will be ok. That's not really the point of the delay. The point of the "bus settle" delay is to allow devices to recover from the bus reset that we send at boot. As Justin pointed out, modern devices take a relatively short period of time to do this (100ms or so), but older devices may take longer. During the bus settle delay, no commands are sent to the devices on the bus. So the delay can't be to allow the device to respond to an inquiry, since during the delay we haven't sent an inquiry. > > The SCSI delay is 10 seconds. > > It used to be 5. I think you're both wrong. The SCSI bus settle delay that is set in GENERIC has been 15 seconds for a VERY long time. I've got a GENERIC config file from a 2.1.7.1 box that's got a SCSI_DELAY of 15 seconds, and I'm pretty sure it was around a long time before that even. The default bus settle delay (SCSI_DELAY) when you don't specify one in the config file has been 2 seconds for a similarly long period of time. CAM doesn't change either one of those values; we just specify the delay in milliseconds, and allow the user to set it to a lower limit of 100ms. Ken -- Kenneth Merry ken@plutotech.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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