[SCSI] lpfc 8.3.40: Clarified the behavior of the lpfc_max_luns module parameter
Signed-off-by: James Smart <james.smart@emulex.com> Signed-off-by: James Bottomley <JBottomley@Parallels.com>
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/*******************************************************************
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* This file is part of the Emulex Linux Device Driver for *
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* Fibre Channel Host Bus Adapters. *
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* Copyright (C) 2004-2012 Emulex. All rights reserved. *
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* Copyright (C) 2004-2013 Emulex. All rights reserved. *
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* EMULEX and SLI are trademarks of Emulex. *
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* www.emulex.com *
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* Portions Copyright (C) 2004-2005 Christoph Hellwig *
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@ -4070,11 +4070,28 @@ LPFC_VPORT_ATTR(discovery_threads, 32, 1, 64, "Maximum number of ELS commands "
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"during discovery");
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/*
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# lpfc_max_luns: maximum allowed LUN.
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# lpfc_max_luns: maximum allowed LUN ID. This is the highest LUN ID that
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# will be scanned by the SCSI midlayer when sequential scanning is
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# used; and is also the highest LUN ID allowed when the SCSI midlayer
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# parses REPORT_LUN responses. The lpfc driver has no LUN count or
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# LUN ID limit, but the SCSI midlayer requires this field for the uses
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# above. The lpfc driver limits the default value to 255 for two reasons.
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# As it bounds the sequential scan loop, scanning for thousands of luns
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# on a target can take minutes of wall clock time. Additionally,
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# there are FC targets, such as JBODs, that only recognize 8-bits of
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# LUN ID. When they receive a value greater than 8 bits, they chop off
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# the high order bits. In other words, they see LUN IDs 0, 256, 512,
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# and so on all as LUN ID 0. This causes the linux kernel, which sees
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# valid responses at each of the LUN IDs, to believe there are multiple
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# devices present, when in fact, there is only 1.
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# A customer that is aware of their target behaviors, and the results as
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# indicated above, is welcome to increase the lpfc_max_luns value.
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# As mentioned, this value is not used by the lpfc driver, only the
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# SCSI midlayer.
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# Value range is [0,65535]. Default value is 255.
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# NOTE: The SCSI layer might probe all allowed LUN on some old targets.
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*/
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LPFC_VPORT_ATTR_R(max_luns, 255, 0, 65535, "Maximum allowed LUN");
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LPFC_VPORT_ATTR_R(max_luns, 255, 0, 65535, "Maximum allowed LUN ID");
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/*
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# lpfc_poll_tmo: .Milliseconds driver will wait between polling FCP ring.
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