linux-kernel - [PATCH] MPILIB: disable usage of floating point registers on parisc

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Date:	Mon, 6 May 2013 00:08:22 +0200
From:	Helge Deller <deller@....de>
To:	Dmitry Kasatkin <dmitry.kasatkin@...el.com>,
	Linux Kernel Development <linux-kernel@...r.kernel.org>,
	linux-parisc@...r.kernel.org
Subject: [PATCH] MPILIB: disable usage of floating point registers on parisc

The umul_ppmm() macro for parisc uses the xmpyu assembler statement
which does calculation via a floating point register.

But usage of floating point registers inside the Linux kernel are not
allowed and gcc will stop compilation due to the -mdisable-fpregs
compiler option.

Fix this by disabling the umul_ppmm() and udiv_qrnnd() macros. The
mpilib will then use the generic built-in implementations instead.

Signed-off-by: Helge Deller <deller@....de>

diff --git a/lib/mpi/longlong.h b/lib/mpi/longlong.h
index 095ab15..d411355 100644
--- a/lib/mpi/longlong.h
+++ b/lib/mpi/longlong.h
@@ -318,7 +318,8 @@ extern UDItype __udiv_qrnnd();
 	     "rM" ((USItype)(bh)), \
 	     "rM" ((USItype)(al)), \
 	     "rM" ((USItype)(bl)))
-#if defined(_PA_RISC1_1)
+#if 0 && defined(_PA_RISC1_1)
+/* xmpyu uses floating point register which is not allowed in Linux kernel. */
 #define umul_ppmm(wh, wl, u, v) \
 do { \
 	union {UDItype __ll; \
@@ -337,7 +338,7 @@ do { \
 #define UMUL_TIME 40
 #define UDIV_TIME 80
 #endif
-#ifndef LONGLONG_STANDALONE
+#if 0 /* #ifndef LONGLONG_STANDALONE */
 #define udiv_qrnnd(q, r, n1, n0, d) \
 do { USItype __r; \
 	(q) = __udiv_qrnnd(&__r, (n1), (n0), (d)); \
--
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