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From ab1cb8a17c14641dcd9119ca1292b961b370426e Mon Sep 17 00:00:00 2001
From: Wu Zhangjin <wuzhangjin@gmail.com>
Date: Fri, 11 Sep 2009 12:52:28 +0800
Subject: [PATCH] Loongson-2F: Fixup of problems introduced by -mfix-loongson2f-jump of binutils 2.20.1
commit 1699e9f1ed3c9a63920bfe26fef22e8dd69a3fdf in tip.
The -mfix-loongson2f-jump option provided by the binutils 2.20.1 have fixed the
Out-of-order Issue of Loongson-2F described in Chapter 15 of "Loongson2F User
Manual"[1,2], but introduced some problems.
The option changes all of the jumping target to "addr & 0xcfffffff" through the
at($1) register, but for the REBOOT address of loongson-2F: 0xbfc00000, this is
totally wrong, so, this patch try to avoid the problem via telling the
assembler not to use at($1) register.
[1] Loongson2F User Manual(Chinese Version)
http://www.loongson.cn/uploadfile/file/200808211
[2] English Version of Chapter 15:
http://groups.google.com.hk/group/loongson-dev/msg/e0d2e220958f10a6?dmode=source
Reported-and-tested-by: Liu Shiwei <liushiwei@gmail.com>
Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
---
arch/mips/loongson/common/reset.c | 12 +++++++++++-
1 files changed, 11 insertions(+), 1 deletions(-)
diff --git a/arch/mips/loongson/common/reset.c b/arch/mips/loongson/common/reset.c
index 9e10d62..8d1985b 100644
--- a/arch/mips/loongson/common/reset.c
+++ b/arch/mips/loongson/common/reset.c
@@ -39,8 +39,18 @@ static void loongson_restart(char *command)
/* do preparation for reboot */
mach_prepare_reboot();
- /* reboot via jumping to boot base address */
+ /* reboot via jumping to boot base address
+ *
+ * ".set noat" and ".set at" are used to ensure the address not broken
+ * by the -mfix-loongson2f-jump option provided by binutils 2.20.1 and
+ * higher which try to change the jumping address to "addr &
+ * 0xcfffffff" via the at($1) register, this is totally wrong for
+ * 0xbfc00000(LOONGSON_BOOT_BASE).
+ */
+
+ __asm__ __volatile__(".set noat\n");
loongson_reboot();
+ __asm__ __volatile__(".set at\n");
}
static void loongson_poweroff(void)
--
1.7.0.4
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