Fix hw.acpi.os_name by renaming it to hw.acpi.osname. The "_name" suffix

is reserved by the loader, and thus any tunable name with that suffix will
be silently discarded.

Document this in the header and man page so that other developers do not
develop so many bumps on the head after banging it against the wall.

Detective work by:	Mark Santcroos, grehan

4 files changed, 13 insertions, 8 deletions

diff --git a/share/man/man4/acpi.4 b/share/man/man4/acpi.4
index 0da6f60..2a21373 100644
--- a/share/man/man4/acpi.4
+++ b/share/man/man4/acpi.4
@@ -317,7 +317,7 @@ Try increasing this number if you get the error
 Enables calling the VESA reset BIOS vector on the resume path.
 Some graphic chips have problems such as LCD white-out after resume.
 Try setting this to 0 if this causes problems for you.
-.It Va hw.acpi.os_name
+.It Va hw.acpi.osname
 Some systems' ASL may have problems because they look for names
 of Microsoft operating systems.
 This tunable overrides the value of the
diff --git a/sys/boot/forth/loader.conf.5 b/sys/boot/forth/loader.conf.5
index 89a803f..414784e 100644
--- a/sys/boot/forth/loader.conf.5
+++ b/sys/boot/forth/loader.conf.5
@@ -132,6 +132,10 @@ special value
 .Dq abort ,
 which aborts the bootstrap process, use of this setting should be avoided.
 .El
+.Pp
+.Em WARNING:
+developers should never use these suffixes for any kernel environment
+variables (tunables) or conflicts will result.
 .Sh DEFAULT SETTINGS
 Most of
 .Nm Ns 's
diff --git a/sys/dev/acpica/Osd/OsdTable.c b/sys/dev/acpica/Osd/OsdTable.c
index 2f057d2..0b94ad3 100644
--- a/sys/dev/acpica/Osd/OsdTable.c
+++ b/sys/dev/acpica/Osd/OsdTable.c
@@ -38,8 +38,8 @@
 #undef _COMPONENT
 #define _COMPONENT      ACPI_TABLES
 
-static char acpi_os_name[128];
-TUNABLE_STR("hw.acpi.os_name", acpi_os_name, sizeof(acpi_os_name));
+static char acpi_osname[128];
+TUNABLE_STR("hw.acpi.osname", acpi_osname, sizeof(acpi_osname));
 
 ACPI_STATUS
 AcpiOsPredefinedOverride (
@@ -50,11 +50,9 @@ AcpiOsPredefinedOverride (
 	return (AE_BAD_PARAMETER);
 
     *NewVal = NULL;
-    if (strncmp(InitVal->Name, "_OS_", 4) == 0 &&
-	getenv_string("hw.acpi.os_name", acpi_os_name, sizeof(acpi_os_name))) {
-
-	printf("ACPI: Overriding _OS definition with \"%s\"\n", acpi_os_name);
-	*NewVal = acpi_os_name;
+    if (strncmp(InitVal->Name, "_OS_", 4) == 0 && strlen(acpi_osname) > 0) {
+	printf("ACPI: Overriding _OS definition with \"%s\"\n", acpi_osname);
+	*NewVal = acpi_osname;
     }
 
     return (AE_OK);
diff --git a/sys/sys/kernel.h b/sys/sys/kernel.h
index fe75bf2..d0f449d 100644
--- a/sys/sys/kernel.h
+++ b/sys/sys/kernel.h
@@ -265,6 +265,9 @@ void	sysinit_add(struct sysinit **set, struct sysinit **set_end);
  * Infrastructure for tunable 'constants'.  Value may be specified at compile
  * time or kernel load time.  Rules relating tunables together can be placed
  * in a SYSINIT function at SI_SUB_TUNABLES with SI_ORDER_LAST.
+ *
+ * WARNING: developers should never use the reserved suffixes specified in
+ * loader.conf(5) for any tunables or conflicts will result.
  */
 
 extern void tunable_int_init(void *);