From 7a2c88509bea849196ed4b77cf10512c4ff40cce Mon Sep 17 00:00:00 2001
From: rsc <devnull@localhost>
Date: Mon, 17 Jan 2005 21:30:05 +0000
Subject: [PATCH] allow config to override kernel version

---
 INSTALL                    | 18 ++++++++++++++++++
 src/libthread/pthread.c    | 17 +++++++++++++++++
 src/libthread/sysofiles.sh |  4 +++-
 src/libthread/threadimpl.h |  1 +
 src/mkhdr                  |  2 --
 5 files changed, 39 insertions(+), 3 deletions(-)

diff --git a/INSTALL b/INSTALL
index 209436a8..9a641aef 100755
--- a/INSTALL
+++ b/INSTALL
@@ -3,7 +3,25 @@
 PLAN9=`pwd` export PLAN9
 PATH=$PLAN9/bin:$PATH export PATH
 
+echo "Resetting $PLAN9/config"
+rm -f $PLAN9/config
+
 (
+if [ `uname` = Linux ]; then
+	# On Linux, we use the kernel version to decide whether
+	# to use pthreads or not.  On 2.6 versions that aren't
+	# linking with NPTL by default, pretend to be an older kernel.
+	echo "Running on Linux: checking for NPTL..."
+	gcc lib/linux-isnptl.c
+	if ./a.out
+	then	
+		echo "	NPTL found."
+		echo "SYSVERSION=2.6" >$PLAN9/config
+	else
+		echo "	NPTL not found."
+		echo "SYSVERSION=2.4" >$PLAN9/config
+	fi
+fi
 echo "Building mk..."
 cd src
 make
diff --git a/src/libthread/pthread.c b/src/libthread/pthread.c
index dbeda7e4..31cc12e1 100644
--- a/src/libthread/pthread.c
+++ b/src/libthread/pthread.c
@@ -133,6 +133,23 @@ _threadsetproc(Proc *p)
 void
 _pthreadinit(void)
 {
+	static struct utsname un;
+	pthread_t id;
+
+	if(uname(&un) < 0){
+		fprint(2, "warning: uname failed: %r\n");
+		goto Okay;
+	}
+	if(strcmp(un.sysname, "Linux") == 0){
+		/*
+		 * Want to distinguish between the old LinuxThreads pthreads
+		 * and the new NPTL implementation.  NPTL uses much bigger
+		 * thread IDs.
+		 */
+		id = pthread_self();
+		if(*(ulong*)&id < 1024*1024)
+			sysfatal("cannot use LinuxThreads as pthread library; see %s/src/libthread/README.Linux", get9root());
+	}
 	pthread_key_create(&prockey, 0);
 }
 
diff --git a/src/libthread/sysofiles.sh b/src/libthread/sysofiles.sh
index 802faf76..a7af0f5b 100644
--- a/src/libthread/sysofiles.sh
+++ b/src/libthread/sysofiles.sh
@@ -1,6 +1,8 @@
 #!/bin/sh
 
-tag="$OBJTYPE-$SYSNAME-`uname -r`-${CC9:-cc}"
+test -f $PLAN9/config && . $PLAN9/config
+
+tag="$OBJTYPE-$SYSNAME-${SYSVERSION:-`uname -r`}-${CC9:-cc}"
 case "$tag" in
 *-Linux-2.6.*)
 	echo pthread.o
diff --git a/src/libthread/threadimpl.h b/src/libthread/threadimpl.h
index 842b81d8..cb5b0168 100644
--- a/src/libthread/threadimpl.h
+++ b/src/libthread/threadimpl.h
@@ -6,6 +6,7 @@
 #include <sched.h>
 #include <signal.h>
 #include <ucontext.h>
+#include <sys/utsname.h>
 #include "libc.h"
 #include "thread.h"
 
diff --git a/src/mkhdr b/src/mkhdr
index 6456aece..38ea8145 100644
--- a/src/mkhdr
+++ b/src/mkhdr
@@ -7,8 +7,6 @@ OBJTYPE=`uname -m | sed '
 	s;ppc64;power;g;
 	s;ppc;power;g'`
 
-SYSVERSION=`uname -r`
-
 BIN=$PLAN9/bin
 LIBDIR=$PLAN9/lib