Chris Zankel writes:

The following patches add support for the Xtensa processor architecture
to uClibc. They are based on a recent SVN checkout (12/05/2007).

The first patch (attached to this post) adds Xtensa support to various
shared configuration and make files. The following patches then include
the Xtensa specific files and directories.

I welcome any feedback and would appreciate it if you could include the
patches into the mainline tree. I am certainly committed to maintain the port. 

Bob Wilson was kind enough to review the patches.

Some notes about the architecture: Xtensa is a configurable and
extensible processor architecture developed by Tensilica. For more
information, please visit: www.linux-xtensa.org.

1 files changed, 42 insertions, 0 deletions

diff --git a/libc/sysdeps/linux/xtensa/syscall.S b/libc/sysdeps/linux/xtensa/syscall.S
new file mode 100644
index 000000000..955e889cf
--- /dev/null
+++ b/libc/sysdeps/linux/xtensa/syscall.S
@@ -0,0 +1,42 @@
+/* Copyright (C) 2005, 2007 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, write to the Free
+   Software Foundation, Inc., 51 Franklin Street - Fifth Floor,
+   Boston, MA 02110-1301, USA.  */
+
+#include "sysdep.h"
+
+/* The register layout upon entering the function is:
+
+   arguments	syscall number	arg0, arg1, arg2, arg3, arg4, arg5
+   ---------	--------------	----------------------------------
+   function	a2		a3,   a4,   a5,   a6,   a7,   (sp)
+   syscall	a2		a6,   a3,   a4,   a5,   a8,   a9
+ */
+
+ENTRY (syscall)
+	l32i	a9, a1, 16	/* load extra argument from stack */
+	mov	a8, a7
+	mov	a7, a3		/* preserve a3 in a7 */
+	mov	a3, a4
+	mov	a4, a5
+	mov	a5, a6
+	mov	a6, a7
+	syscall
+	movi    a4, -4095
+	bgeu    a2, a4, SYSCALL_ERROR_LABEL
+.Lpseudo_end:
+	retw
+PSEUDO_END (syscall)