Re-enable CTL in GENERIC on i386 and amd64, but turn on the CTL disable

tunable by default.

This will allow GENERIC configurations to boot on small memory boxes, but
not require end users who want to use CTL to recompile their kernel.  They
can simply set kern.cam.ctl.disable=0 in loader.conf.

The eventual solution to the memory usage problem is to change the way
CTL allocates memory to be more configurable, but this should fix things
for small memory situations in the mean time.

UPDATING:		Explain the change in the CTL configuration, and
			how users can enable CTL if they would like to use
			it.

sys/conf/options:	Add a new option, CTL_DISABLE, that prevents CTL
			from initializing.

ctl.c:			If CTL_DISABLE is turned on, don't initialize.

i386/conf/GENERIC,
amd64/conf/GENERIC:	Re-enable device ctl, and add the CTL_DISABLE
			option.

5 files changed, 24 insertions, 2 deletions

diff --git a/UPDATING b/UPDATING
index 50e6452..ef79fa8 100644
--- a/UPDATING
+++ b/UPDATING
@@ -26,6 +26,13 @@ NOTE TO PEOPLE WHO THINK THAT FreeBSD 10.x IS SLOW:
 	disable the most expensive debugging functionality run
 	"ln -s 'abort:false,junk:false' /etc/malloc.conf".)
 
+20130304:
+	The ctl device has been re-enabled in GENERIC for i386 and amd64,
+	but does not initialize by default (because of the new CTL_DISABLE
+	option) to save memory.  To re-enable it, remove the CTL_DISABLE
+	option from the kernel config file or set kern.cam.ctl.disable=0
+	in /boot/loader.conf.
+
 20130301:
 	The ctl device has been disabled in GENERIC for i386 and amd64.
 	This was done due to the extra memory being allocated at system
diff --git a/sys/amd64/conf/GENERIC b/sys/amd64/conf/GENERIC
index 3988195..577cf4b 100644
--- a/sys/amd64/conf/GENERIC
+++ b/sys/amd64/conf/GENERIC
@@ -138,7 +138,10 @@ device		sa		# Sequential Access (tape etc)
 device		cd		# CD
 device		pass		# Passthrough device (direct ATA/SCSI access)
 device		ses		# Enclosure Services (SES and SAF-TE)
-#device		ctl		# CAM Target Layer
+device		ctl		# CAM Target Layer
+options		CTL_DISABLE	# Disable CTL by default to save memory.
+				# Re-enable with kern.cam.ctl.disable=0 in
+				# /boot/loader.conf
 
 # RAID controllers interfaced to the SCSI subsystem
 device		amr		# AMI MegaRAID
diff --git a/sys/cam/ctl/ctl.c b/sys/cam/ctl/ctl.c
index 768332e..1884c7b 100644
--- a/sys/cam/ctl/ctl.c
+++ b/sys/cam/ctl/ctl.c
@@ -78,6 +78,8 @@ __FBSDID("$FreeBSD$");
 #include <cam/ctl/ctl_scsi_all.h>
 #include <cam/ctl/ctl_error.h>
 
+#include "opt_ctl.h"
+
 struct ctl_softc *control_softc = NULL;
 
 /*
@@ -317,7 +319,11 @@ static int persis_offset;
 static uint8_t ctl_pause_rtr;
 static int     ctl_is_single;
 static int     index_to_aps_page;
+#ifdef CTL_DISABLE
+int	   ctl_disable = 1;
+#else
 int	   ctl_disable = 0;
+#endif
 
 SYSCTL_NODE(_kern_cam, OID_AUTO, ctl, CTLFLAG_RD, 0, "CAM Target Layer");
 SYSCTL_INT(_kern_cam_ctl, OID_AUTO, disable, CTLFLAG_RDTUN, &ctl_disable, 0,
diff --git a/sys/conf/options b/sys/conf/options
index 75d0c97..ec9271d 100644
--- a/sys/conf/options
+++ b/sys/conf/options
@@ -329,6 +329,9 @@ SCSI_PT_DEFAULT_TIMEOUT	opt_pt.h
 # Options used only in cam/scsi/scsi_ses.c
 SES_ENABLE_PASSTHROUGH	opt_ses.h
 
+# Options used only in cam/ctl
+CTL_DISABLE		opt_ctl.h
+
 # Options used in dev/sym/ (Symbios SCSI driver).
 SYM_SETUP_LP_PROBE_MAP	opt_sym.h	#-Low Priority Probe Map (bits)
 					# Allows the ncr to take precedence
diff --git a/sys/i386/conf/GENERIC b/sys/i386/conf/GENERIC
index 3a98ded..d35a780 100644
--- a/sys/i386/conf/GENERIC
+++ b/sys/i386/conf/GENERIC
@@ -146,7 +146,10 @@ device		sa		# Sequential Access (tape etc)
 device		cd		# CD
 device		pass		# Passthrough device (direct ATA/SCSI access)
 device		ses		# Enclosure Services (SES and SAF-TE)
-#device		ctl		# CAM Target Layer
+device		ctl		# CAM Target Layer
+options		CTL_DISABLE	# Disable CTL by default to save memory.
+				# Re-enable with kern.cam.ctl.disable=0 in
+				# /boot/loader.conf
 
 # RAID controllers interfaced to the SCSI subsystem
 device		amr		# AMI MegaRAID