Hi, Patrick
I have tried to the patch you mentioned below against 2.4.7.
It avoids the panic when I tries to set max_scsi_luns=128
for a aic7xxx.o driver used for a SPAESE_LUN type device.
But what bothers me is that the scsi scan stops on shpnt->max_lun,
e.g. 8, in aic7xxx driver case. As Doug Ledford mentioned,
we need to set reasonable values of shpnt->max_lun for
all controllers.
Xiangping Chen
-----Original Message-----
From: Patrick Mansfield [mailto:patman@sequent.com]
Sent: Monday, September 17, 2001 1:06 PM
To: conway, heather
Cc: 'Alan Cox'; 'linux-scsi@vger.kernel.org';
linux-kernel@vger.kernel.org
Subject: Re: v2.4.9 and sequential scan
On Mon, Sep 17, 2001 at 09:07:25AM -0400, conway, heather wrote:
> Hi Alan,
> I tried two separate hosts, one with the aic7xxx driver using the
AHA-2944UW
> and one with the qla2x00 driver, both running v2.4.9 attached to external
> storage. Both hosts are set to 128 for the max # of SCSI disks top be
> laoded as modules and the kernel has been compiled, but no other patches
or
> tweaks were applied to the kernel. Both hosts panicked upon boot when
> trying to scan the external bus.
> The host attached to the external storage via SCSI (aic7xxx) has The host
> attached via FC with the qla2x00 has only 24 devices assigned to it. The
> qla2x00 driver reports trying to scan up to LUN 509 before timing out and
> panicking. I have tried this a few times and I've seen the host scan up
to
> LUN 814 with the qla2x00 driver. I obtained a serial console trace from
> both hosts and have enclosed them.
> Any thoughts?
> Thanks for the help.
> Heather
Heather -
EMC is in the device_list[] (in scsi_scan.c) as a sparse LUN device.
I don't quite follow your information about aic7xx and SCSI storage.
Doug Ledford posted a patch for this plus one other fix in:
http://marc.theaimsgroup.com/?l=linux-kernel&m=98462326721779&w=2
If you look at the current setting of *max_dev_lun, it either jumps
around (for low values of max_scsi_luns, i.e. 1), or is incremented
by 1/2 of shpnt->max_lun until it reaches max_scsi_luns (for high
values of max_scsi_luns, i.e. 0xffffffff). It is currently modified
(for sparse LUN or force LUN devices) only when you find a LUN, but
its value is set each time not just once.
Always setting it to shpnt->max_lun is not very bad - if max_lun is
high, you are on fibre/FCP, and scanning should be very fast
compared to SCSI.
Here's a patch if you want to try it out, it also sets *max_dev_lun
for the early sparse lun check (we don't need the duplicate setting
for the second sparse lun check, but it does return 1 there, so I
left the settings of *max_dev_lun and *sparse_lun).
I've compiled but haven't run with this patch, though I've previously
compiled and run when patched against an earlier version of the
kernel (2.4.5 or so).
-- Patrick Mansfield--- linux-2.4.9/drivers/scsi/scsi_scan.c Mon Aug 13 16:36:30 2001 +++ linux-2.4.9-maxlun/drivers/scsi/scsi_scan.c Mon Sep 17 09:29:53 2001 @@ -579,7 +579,8 @@ bflags = get_device_flags (scsi_result); if (bflags & BLIST_SPARSELUN) { - *sparse_lun = 1; + *max_dev_lun = shpnt->max_lun; + *sparse_lun = 1; } /* * Check the peripheral qualifier field - this tells us whether LUNS @@ -795,19 +796,7 @@ * other settings, and scan all of them. */ if (bflags & BLIST_SPARSELUN) { - /* - * Scanning MAX_SCSI_LUNS units would be a bad idea. - * Any better idea? - * I think we need REPORT LUNS in future to avoid scanning - * of unused LUNs. But, that is another item. - * - * FIXME(eric) - perhaps this should be a kernel configurable? - */ - if (*max_dev_lun < shpnt->max_lun) - *max_dev_lun = shpnt->max_lun; - else if ((max_scsi_luns >> 1) >= *max_dev_lun) - *max_dev_lun += shpnt->max_lun; - else *max_dev_lun = max_scsi_luns; + *max_dev_lun = shpnt->max_lun; *sparse_lun = 1; return 1; } @@ -816,17 +805,7 @@ * settings, and scan all of them. */ if (bflags & BLIST_FORCELUN) { - /* - * Scanning MAX_SCSI_LUNS units would be a bad idea. - * Any better idea? - * I think we need REPORT LUNS in future to avoid scanning - * of unused LUNs. But, that is another item. - */ - if (*max_dev_lun < shpnt->max_lun) - *max_dev_lun = shpnt->max_lun; - else if ((max_scsi_luns >> 1) >= *max_dev_lun) - *max_dev_lun += shpnt->max_lun; - else *max_dev_lun = max_scsi_luns; + *max_dev_lun = shpnt->max_lun; return 1; } /*
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This archive was generated by hypermail 2b29 : Sun Sep 23 2001 - 21:00:20 EST