Clarified the behavior of the lpfc_max_luns module parameter Signed-off-by: James Smart <james.smart@xxxxxxxxxx> --- lpfc_attr.c | 23 ++++++++++++++++++++--- 1 file changed, 20 insertions(+), 3 deletions(-) diff -upNr a/drivers/scsi/lpfc/lpfc_attr.c b/drivers/scsi/lpfc/lpfc_attr.c --- a/drivers/scsi/lpfc/lpfc_attr.c 2013-05-03 09:24:34.000000000 -0400 +++ b/drivers/scsi/lpfc/lpfc_attr.c 2013-05-31 10:58:23.785057766 -0400 @@ -1,7 +1,7 @@ /******************************************************************* * This file is part of the Emulex Linux Device Driver for * * Fibre Channel Host Bus Adapters. * - * Copyright (C) 2004-2012 Emulex. All rights reserved. * + * Copyright (C) 2004-2013 Emulex. All rights reserved. * * EMULEX and SLI are trademarks of Emulex. * * www.emulex.com * * Portions Copyright (C) 2004-2005 Christoph Hellwig * @@ -4070,11 +4070,28 @@ LPFC_VPORT_ATTR(discovery_threads, 32, 1 "during discovery"); /* -# lpfc_max_luns: maximum allowed LUN. +# lpfc_max_luns: maximum allowed LUN ID. This is the highest LUN ID that +# will be scanned by the SCSI midlayer when sequential scanning is +# used; and is also the highest LUN ID allowed when the SCSI midlayer +# parses REPORT_LUN responses. The lpfc driver has no LUN count or +# LUN ID limit, but the SCSI midlayer requires this field for the uses +# above. The lpfc driver limits the default value to 255 for two reasons. +# As it bounds the sequential scan loop, scanning for thousands of luns +# on a target can take minutes of wall clock time. Additionally, +# there are FC targets, such as JBODs, that only recognize 8-bits of +# LUN ID. When they receive a value greater than 8 bits, they chop off +# the high order bits. In other words, they see LUN IDs 0, 256, 512, +# and so on all as LUN ID 0. This causes the linux kernel, which sees +# valid responses at each of the LUN IDs, to believe there are multiple +# devices present, when in fact, there is only 1. +# A customer that is aware of their target behaviors, and the results as +# indicated above, is welcome to increase the lpfc_max_luns value. +# As mentioned, this value is not used by the lpfc driver, only the +# SCSI midlayer. # Value range is [0,65535]. Default value is 255. # NOTE: The SCSI layer might probe all allowed LUN on some old targets. */ -LPFC_VPORT_ATTR_R(max_luns, 255, 0, 65535, "Maximum allowed LUN"); +LPFC_VPORT_ATTR_R(max_luns, 255, 0, 65535, "Maximum allowed LUN ID"); /* # lpfc_poll_tmo: .Milliseconds driver will wait between polling FCP ring. -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
