Rename the kern.vm.kmem.size tunable to the more logical vm.kmem_size. To

assure backward compatibility (conditional on !BURN_BRIDGES), look it up
by its old name first, and log a warning (but accept the setting) if it
was found.  If both the old and new name are defined, the new name takes
precedence.

Also export vm.kmem_size as a read-only sysctl variable; I find it hard to
tune a parameter when I don't know its default value, especially when that
default value is computed at boot time.

4 files changed, 14 insertions, 8 deletions

diff --git a/sys/boot/common/help.common b/sys/boot/common/help.common
index a6fd748..8b68157 100644
--- a/sys/boot/common/help.common
+++ b/sys/boot/common/help.common
@@ -244,7 +244,7 @@
 		Set the number of sendfile buffers to be allocated.  This
 		overrides the value determined when the kernel was compiled.
 
-	set kern.vm.kmem.size=<value>		VM_KMEM_SIZE
+	set vm.kmem_size=<value>		VM_KMEM_SIZE
 
 		Sets the size of kernel memory (bytes).  This overrides
 		the value determined when the kernel was compiled.
diff --git a/sys/boot/common/loader.8 b/sys/boot/common/loader.8
index 2712da1..ef9456b 100644
--- a/sys/boot/common/loader.8
+++ b/sys/boot/common/loader.8
@@ -451,11 +451,6 @@ Set the number of
 buffers to be allocated.
 Overrides
 .Dv NSFBUFS .
-.It Va kern.vm.kmem.size
-Sets the size of kernel memory (bytes).
-This overrides the value determined when the kernel was compiled.
-Modifies
-.Va VM_KMEM_SIZE .
 .It Va kern.maxswzone
 Limits the amount of KVM to be used to hold swap
 meta information, which directly governs the
@@ -499,6 +494,11 @@ Overrides the compile-time set value of
 or the preset default of 512.
 Must be a power of 2.
 .El
+.It Va vm.kmem_size
+Sets the size of kernel memory (bytes).
+This overrides the value determined when the kernel was compiled.
+Modifies
+.Va VM_KMEM_SIZE .
 .Ss BUILTIN PARSER
 When a builtin command is executed, the rest of the line is taken
 by it as arguments, and it is processed by a special parser which
diff --git a/sys/boot/forth/loader.conf b/sys/boot/forth/loader.conf
index 18c34d0..48791d7 100644
--- a/sys/boot/forth/loader.conf
+++ b/sys/boot/forth/loader.conf
@@ -96,10 +96,10 @@ module_path="/boot/kernel;/boot/modules"	# Set the module search path
 #kern.ipc.nmbclusters=""	# Set the number of mbuf clusters
 #kern.ipc.nmbufs=""		# Set the maximum number of mbufs
 #kern.ipc.nsfbufs=""		# Set the number of sendfile(2) bufs
-#kern.vm.kmem.size=""		# Sets the size of kernel memory (bytes)
 #net.inet.tcp.tcbhashsize=""	# Set the value of TCBHASHSIZE
 #vfs.root.mountfrom=""		# Specify root partition in a way the
 				# kernel understands
+#vm.kmem_size=""		# Sets the size of kernel memory (bytes)
 #debug.ktr.cpumask="0xf"	# Bitmask of CPUs to enable KTR on
 #debug.ktr.mask="0x1200"	# Bitmask of KTR events to enable
 #debug.ktr.verbose="1"		# Enable console dump of KTR events
diff --git a/sys/kern/kern_malloc.c b/sys/kern/kern_malloc.c
index 62fc909..cbcbe9e 100644
--- a/sys/kern/kern_malloc.c
+++ b/sys/kern/kern_malloc.c
@@ -133,6 +133,8 @@ struct {
 };
 
 u_int vm_kmem_size;
+SYSCTL_UINT(_vm, OID_AUTO, kmem_size, CTLFLAG_RD, &vm_kmem_size, 0,
+    "Size of kernel memory");
 
 /*
  * The malloc_mtx protects the kmemstatistics linked list.
@@ -444,7 +446,11 @@ kmeminit(dummy)
 #endif
 
 	/* Allow final override from the kernel environment */
-	TUNABLE_INT_FETCH("kern.vm.kmem.size", &vm_kmem_size);
+#ifndef BURN_BRIDGES
+	if (TUNABLE_INT_FETCH("kern.vm.kmem.size", &vm_kmem_size) != 0)
+		printf("kern.vm.kmem.size is now called vm.kmem_size!\n");
+#endif
+	TUNABLE_INT_FETCH("vm.kmem_size", &vm_kmem_size);
 
 	/*
 	 * Limit kmem virtual size to twice the physical memory.