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- Cosmetics git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@437 d57e44dd-8a1f-0410-8b47-8ef2f437770f
77 lines
2.9 KiB
Plaintext
77 lines
2.9 KiB
Plaintext
Target driver for LSI/MPT XXX cards
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===================================
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Version X.X.X, XX XXX 200X
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--------------------------
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This driver was originally developed by Hu Gang and then is developed by
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Erik Habbinga <erikhabbinga@inphase-tech.com>. It is on the early stage
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of development.
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The current maintainer of this driver is Erik. Please send him all
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question related to it (CC: scst-devel@lists.sourceforge.net).
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Building from the Linux kernel tree
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-----------------------------------
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To build from the kernel tree, you should:
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1. Link drivers/message/fusion/mpt_scst to $(SCST_DIR)/mpt.
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2. Copy or link Makefile and Kconfig from $(SCST_DIR)/mpt/in-tree to
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$(SCST_DIR)/mpt (Makefile will be replaced).
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3. Patch drivers/message/fusion/Makefile and
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drivers/message/fusion/Kconfig by diffs from $(SCST_DIR)/mpt/in-tree
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4. Correct in drivers/message/fusion/Makefile SCST_INC_DIR variable so
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it points to correct directory with SCST include files.
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Building outside the Linux kernel tree
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--------------------------------------
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Edit Makefile, comment there line
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obj-$(CONFIG_FUSION_SCST) += mpt_scst.o
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and uncomment line
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obj-m += mpt_scst.o
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Notes on implementation
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-----------------------
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The driver takes the mptstm target driver implemented by LSI
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and ports it to the SCST architecture.
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The LSI hardware returns an error when it realizes that command
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status and sense data cannot be sent in the same transaction.
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This happens during non-packetized SCSI command handling (not FC or
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SAS). For SCSI implementations, the driver speculatively caches
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sense data. If the hardware reports that the sense data could not
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be sent, the driver will return the cached sense data without
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involving SCST if the next command is REQUEST SENSE. Cached sense
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data is discarded on bus reset or if the next command after sense
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send failure was not REQUEST SENSE.
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Caching sense data in this fashion probably won't work in a tagged
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command queuing environment. If SCSI hardware is being used, the
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driver inspects responses to the INQUIRY command and clears the
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BQUE and CMDQUE bits in the standard INQUIRY response to disable
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tagged command queuing.
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Known issues
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------------
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Newer versions of SCSI HBA firmware have a bug where the incorrect
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amount of data is transferred for non-divisible-by-4 length transfers
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(like standard 14 byte REQUEST SENSE). It's hit or miss for recently
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bought cards if it has bad firmware or not. Some recently acquired PCIe
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SCSI HBA had a mix of good and bad target firmware. Revision 1.03.29 is
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where it broke, and all the target firmware on LSI's website is 1.03.34,
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which is broken for target mode. As a workaround the SCSI parallel
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transfer rate is forced to very slow asynchronous wide (Fast-5), which
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doesn't quite hit >> 10 MB/sec, depending on the SCSI HBA firmware
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revision. LSI is aware of the problem and the driver will be updated to
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restore functionality upon a new good SCSI HBA firmware release.
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