On Tue, Jan 17, 2006 at 04:17:14PM +0200, P. Christeas wrote:
> On Tuesday 17 January 2006 3:48 pm, Martin Michlmayr wrote:
> > Has anyone else seen the following error when compiling a kernel with GCC
> > 4.0 (GCC 3.3 works) and knows what to do about it?
> >
> > arch/mips/kernel/built-in.o: In function `time_init':
> > : undefined reference to `__lshrdi3'
Thanks to Martin Michlmayr's testing I now know this problem is limited
to kernels built with gcc 4.0 and newer when optimizing for size.
> I think I've solved it by copying the files
> ashldi3.c ashrdi3.c lshrdi3.c
> from arch/ppc/lib to arch/mips/lib
There is an awful lot of libgcc bits flying around in the kernel and I guess
I'd be flamed for submitting even more ;-) so I tried to come up with
something to make most if not all unnecessary. Still needs a little
polishing but below for testing and commenting.
Ralf
diff --git a/include/asm-mips/libgcc.h b/include/asm-mips/libgcc.h
new file mode 100644
index 0000000..0aef711
include/asm-mips/libgcc.h | 8 ++++++++
include/linux/libgcc.h | 32 ++++++++++++++++++++++++++++++++
lib/Makefile | 1 +
lib/ashldi3.c | 32 ++++++++++++++++++++++++++++++++
lib/ashrdi3.c | 36 ++++++++++++++++++++++++++++++++++++
lib/lshrdi3.c | 34 ++++++++++++++++++++++++++++++++++
6 files changed, 143 insertions(+)
Index: linux-mips/include/asm-mips/libgcc.h
===================================================================
--- /dev/null
+++ linux-mips/include/asm-mips/libgcc.h
@@ -0,0 +1,8 @@
+#ifndef __ASM_LIBGCC_H
+#define __ASM_LIBGCC_H
+
+#define ARCH_NEEDS_ashldi3
+#define ARCH_NEEDS_ashrdi3
+#define ARCH_NEEDS_lshrdi3
+
+#endif /* __ASM_LIBGCC_H */
Index: linux-mips/include/linux/libgcc.h
===================================================================
--- /dev/null
+++ linux-mips/include/linux/libgcc.h
@@ -0,0 +1,32 @@
+#ifndef __LINUX_LIBGCC_H
+#define __LINUX_LIBGCC_H
+
+#include <asm/byteorder.h>
+#include <asm/libgcc.h>
+
+typedef long long DWtype;
+typedef int Wtype;
+typedef unsigned int UWtype;
+typedef int word_type __attribute__ ((mode (__word__)));
+
+#define BITS_PER_UNIT 8
+
+#ifdef __BIG_ENDIAN
+struct DWstruct {
+ Wtype high, low;
+};
+#elif defined(__LITTLE_ENDIAN)
+struct DWstruct {
+ Wtype low, high;
+};
+#else
+#error I feel sick.
+#endif
+
+typedef union
+{
+ struct DWstruct s;
+ DWtype ll;
+} DWunion;
+
+#endif /* __LINUX_LIBGCC_H */
Index: linux-mips/lib/Makefile
===================================================================
--- linux-mips.orig/lib/Makefile
+++ linux-mips/lib/Makefile
@@ -8,6 +8,7 @@ lib-y := errno.o ctype.o string.o vsprin
sha1.o
lib-y += kobject.o kref.o kobject_uevent.o klist.o
+lib-y += ashldi3.o ashrdi3.o lshrdi3.o
obj-y += sort.o parser.o halfmd4.o
Index: linux-mips/lib/ashldi3.c
===================================================================
--- /dev/null
+++ linux-mips/lib/ashldi3.c
@@ -0,0 +1,32 @@
+#include <linux/libgcc.h>
+#include <linux/module.h>
+
+#ifdef ARCH_NEEDS_ashldi3
+
+DWtype __ashldi3(DWtype u, word_type b)
+{
+ DWunion uu, w;
+ word_type bm;
+
+ if (b == 0)
+ return u;
+
+ uu.ll = u;
+ bm = (sizeof(Wtype) * BITS_PER_UNIT) - b;
+
+ if (bm <= 0) {
+ w.s.low = 0;
+ w.s.high = (UWtype) uu.s.low << -bm;
+ } else {
+ const UWtype carries = (UWtype) uu.s.low >> bm;
+
+ w.s.low = (UWtype) uu.s.low << b;
+ w.s.high = ((UWtype) uu.s.high << b) | carries;
+ }
+
+ return w.ll;
+}
+
+EXPORT_SYMBOL(__ashldi3);
+
+#endif /* ARCH_NEEDS_ashldi3 */
Index: linux-mips/lib/ashrdi3.c
===================================================================
--- /dev/null
+++ linux-mips/lib/ashrdi3.c
@@ -0,0 +1,36 @@
+#include <linux/libgcc.h>
+#include <linux/module.h>
+
+/* Unless shift functions are defined with full ANSI prototypes,
+ parameter b will be promoted to int if word_type is smaller than an int. */
+#ifdef ARCH_NEEDS_ashrdi3
+
+DWtype __ashrdi3(DWtype u, word_type b)
+{
+ DWunion uu, w;
+ word_type bm;
+
+ if (b == 0)
+ return u;
+
+ uu.ll = u;
+ bm = (sizeof(Wtype) * BITS_PER_UNIT) - b;
+
+ if (bm <= 0) {
+ /* w.s.high = 1..1 or 0..0 */
+ w.s.high =
+ uu.s.high >> (sizeof(Wtype) * BITS_PER_UNIT - 1);
+ w.s.low = uu.s.high >> -bm;
+ } else {
+ const UWtype carries = (UWtype) uu.s.high << bm;
+
+ w.s.high = uu.s.high >> b;
+ w.s.low = ((UWtype) uu.s.low >> b) | carries;
+ }
+
+ return w.ll;
+}
+
+EXPORT_SYMBOL(__ashrdi3);
+
+#endif /* ARCH_NEEDS_ashrdi3 */
Index: linux-mips/lib/lshrdi3.c
===================================================================
--- /dev/null
+++ linux-mips/lib/lshrdi3.c
@@ -0,0 +1,34 @@
+#include <linux/libgcc.h>
+#include <linux/module.h>
+
+/* Unless shift functions are defined with full ANSI prototypes,
+ parameter b will be promoted to int if word_type is smaller than an int. */
+#ifdef ARCH_NEEDS_lshrdi3
+
+DWtype __lshrdi3(DWtype u, word_type b)
+{
+ DWunion uu, w;
+ word_type bm;
+
+ if (b == 0)
+ return u;
+
+ uu.ll = u;
+ bm = (sizeof(Wtype) * BITS_PER_UNIT) - b;
+
+ if (bm <= 0) {
+ w.s.high = 0;
+ w.s.low = (UWtype) uu.s.high >> -bm;
+ } else {
+ const UWtype carries = (UWtype) uu.s.high << bm;
+
+ w.s.high = (UWtype) uu.s.high >> b;
+ w.s.low = ((UWtype) uu.s.low >> b) | carries;
+ }
+
+ return w.ll;
+}
+
+EXPORT_SYMBOL(__lshrdi3);
+
+#endif /* ARCH_NEEDS_lshrdi3 */
