Date: Tue, 2 May 1995 07:51:37 -0400 (EDT) From: Peter Dufault <dufault@hda.com> To: bde@zeta.org.au (Bruce Evans) Cc: current@FreeBSD.org, joerg@FreeBSD.org Subject: opening dead devices and slices Message-ID: <199505021151.HAA26220@hda.com> In-Reply-To: <199505020515.PAA21076@godzilla.zeta.org.au> from "Bruce Evans" at May 2, 95 03:15:44 pm
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Bruce Evans writes:
>
> >The problem in question is:
>
> >sd1(bt0:1:0): MEDIUM ERROR asc:31,0 Medium format corrupted field replaceable unit: 31
> >, retries:4
> >...
> >sd1: error reading primary partition table reading fsbn 0 (sd1 bn 0; cn 0 tn 0 sn 0)
>
>
> >...a chicken-and-egg problem. How to format a disk that is not
> >accessible since its not formatted properly?
>
> There will have to be no such thing as an error in xdopen(whole_disk_dev)
> (again :-(). There will have to be verbose error messages instead :-).
>
> Why don't we have O_IOCTLONLY or O_NOACCESS access modes?
Because of permissions issues? I like having the ability to protect
the ioctl-only devices using the usual permissions. Plus I've never
heard of O_IOCTLONLY mode :). Joerg's suggestion for O_NONBLOCK
is reasonable if you read the SCSI spec:
"If O_NONBLOCK is set: The open() shall return without waiting for the
device to be ready or available. Subsequent behavior of the device is
device-specific".
I've made this change locally in scsiconf.h and want to commit it;
is there anyway we can make it play with slices?
/* Device number fields:
*
* NON-FIXED SCSI devices:
*
* FC?? ???? ???? ???? MMMMMMMM mmmmmmmm
*
* F: Fixed device (nexus in number): must be 0.
* C: Control device; only user mode ioctl is supported.
* ?: Don't know; those bits didn't use to exist, currently always 0.
* M: Major device number.
* m: Old style minor device number.
*
* FIXED SCSI devices:
*
* XXX Conflicts with the slice code. Maybe the slice code can be
* changed to respect the F bit?
*
* FC?? ?BBB TTTT ?LLL MMMMMMMM mmmmmmmm
*
* F: Fixed device (nexus in number); must be 1.
* C: Control device; only user mode ioctl is supported.
* B: SCSI bus
* T: SCSI target ID
* L: Logical unit
* M: Major device number
* m: Old style minor device number.
*/
#define SCSI_FIXED(DEV) (((DEV) & 0x80000000) >> 31)
#define SCSI_CONTROL(DEV) (((DEV) & 0x40000000) >> 30)
#define SCSI_BUS(DEV) (((DEV) & 0x07000000) >> 24)
#define SCSI_ID(DEV) (((DEV) & 0x00F00000) >> 20)
#define SCSI_LUN(DEV) (((DEV) & 0x00070000) >> 16)
#define SCSI_MKFIXED(B, T, L) ( \
((B) << 24) | \
((T) << 20) | \
((L) << 16) | \
( 1 << 31) )
--
Peter Dufault Real Time Machine Control and Simulation
HD Associates, Inc. Voice: 508 433 6936
dufault@hda.com Fax: 508 433 5267
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