From 1dd534e2aa2d146dfa3860845cd826e3b641c98a Mon Sep 17 00:00:00 2001
From: Vladislav Bolkhovitin <vst@vlnb.net>
Date: Thu, 31 May 2007 15:13:13 +0000
Subject: [PATCH] Some docs updates

git-svn-id: http://svn.code.sf.net/p/scst/svn/trunk@118 d57e44dd-8a1f-0410-8b47-8ef2f437770f
---
 scst/README     | 29 ++++++++++++++++-------------
 scst/src/scst.c |  5 +++++
 2 files changed, 21 insertions(+), 13 deletions(-)

diff --git a/scst/README b/scst/README
index 2e1c61358..0d12e761a 100644
--- a/scst/README
+++ b/scst/README
@@ -423,22 +423,25 @@ IMPORTANT: Since data in BLOCKIO and FILEIO modes are not consistent between
 Pass-through mode
 -----------------
 
-As any other hardware, a local SCSI hardware for devices on target,
-which are exported in the pass-through mode, can not handle commands
-with amount of data and/or segments count in scatter-gather array
-bigger, than some values. Therefore, when using the pass-through mode
-you should note that the corresponding values on the corresponding
-devices on initiators can not be bigger, than values, which the hardware
-on the target can support. Otherwise you will see symptoms like small
-transfers work well, but large ones stall and messages like: "Unable to
-complete command due to SG IO count limitation" are printed in the
-kernel logs.
+In the pass-through mode (i.e. using the pass-through device handlers
+scst_disk, scst_tape, etc) SCSI commands, coming from remote initiators,
+are passed to local SCSI hardware on target as is, without any
+modifications. As any other hardware, the local SCSI hardware can not
+handle commands with amount of data and/or segments count in
+scatter-gather array bigger some values. Therefore, when using the
+pass-through mode you should note that values for maximum number of
+segments and maximum amount of transferred data for each SCSI command on
+devices on initiators can not be bigger, than corresponding values of
+the corresponding SCSI devices on the target. Otherwise you will see
+symptoms like small transfers work well, but large ones stall and
+messages like: "Unable to complete command due to SG IO count
+limitation" are printed in the kernel logs.
 
 You can't control from the user space limit of the scatter-gather
 segments, but for block devices usually it is sufficient if you set on
-the initiator /sys/block/DEVICE_NAME/queue/max_sectors_kb in the same or
-lower value as in /sys/block/DEVICE_NAME/queue/max_hw_sectors_kb for the
-corresponding device on the target.
+the initiators /sys/block/DEVICE_NAME/queue/max_sectors_kb in the same
+or lower value as in /sys/block/DEVICE_NAME/queue/max_hw_sectors_kb for
+the corresponding devices on the target.
 
 For not-block devices SCSI commands are usually generated directly by
 applications, so, if you experience large transfers stalls, you should
diff --git a/scst/src/scst.c b/scst/src/scst.c
index 39f722e63..853346c67 100644
--- a/scst/src/scst.c
+++ b/scst/src/scst.c
@@ -32,6 +32,11 @@
 #include "scst_priv.h"
 #include "scst_mem.h"
 
+#ifndef CONFIG_NOHIGHMEM
+#warning HIGHMEM kernel configurations are supported, but not recommended. \
+	Consider changing VMSPLIT option or using 64-bit configuration instead.
+#endif
+
 /*
  * All targets, devices and dev_types management is done under
  * this mutex.