Date: Thu, 1 Oct 1998 09:48:48 +1000 From: Bruce Evans <bde@zeta.org.au> To: karl@Denninger.Net, toasty@home.dragondata.com Cc: bright@hotjobs.com, current@FreeBSD.ORG, dnelson@emsphone.com, tom@uniserve.com Subject: Re: Long IDE probes? Message-ID: <199809302348.JAA23414@godzilla.zeta.org.au>
next in thread | raw e-mail | index | archive | help
>To shed some light.... This is all according to the ATA specs: > >We throw a hardware reset. > >The device must set the BSY flag within 400ns, after RESET- is turned off. >If we can see BSY, the device is there. We should be able to stop at this >point, as suposedly this is a yes/no test for a device being present. > >However, after this, we're supposed to do some magic, then the device has 31 >seconds to respond. > >Possibly there are some rogue devices/chipsets out there that fool the >driver with the BSY test, and so we're forced to wait for the full 31 >seconds for the reply? We're supposed to wait 31 seconds for the drives to become unbusy. We actually only wait only 10 seconds (for each drive IIRC). With the current (poorly organised) probe logic, the correct wait time of 31 seconds would give a delay of > 2 minutes when no drives are attached. This should not be surprising. The BIOS also takes minute(s) to time out if it is misconfigured. >Not sure, but that's what the 'standard' is. Do you prefer SCSI, where there is no standard timeout, and the OS guesses that 15 seconds is enough? Bruce To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?199809302348.JAA23414>