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MIPS: Loongson: Add CPU_LOONGSON2F_WORKAROUNDS

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As documented in the  Loongson 2F User Manual [2, 3], the old Loongson2F
series (2F01 / 2F02) have the NOP & JUMP issues which requires workarounds
in the kernel and binutils.  This issue has been rectified in Loongson 2F
series 2F03 so no workarounds needed.

Now that the workarounds [1] adding the the -mfix-loongson2f-nop and
-mfix-loongson2f-jump options have been comitted to the binutils the CVS
repository), we can add the workarounds in the kernel.

The workarounds have no significant side effect on the system but may
decrease performance so we control them through a a new
CPU_LOONGSON2F_WORKAROUNDS config option allowing the users to only enable
it as necessary.

[1] "Fixups of Loongson2F" patch for binutils(actually for gas)
    http://sourceware.org/ml/binutils/2009-11/msg00387.html
[2] Chapter 15 of "Loongson2F User Manual"(Chinese Version)
    http://www.loongson.cn/uploadfile/file/200808211
[3] English Version of the above chapter 15
    http://groups.google.com.hk/group/loongson-dev/msg/e0d2e220958f10a6?dmode=source

Signed-off-by: Wu Zhangjin <wuzhangjin@gmail.com>
Cc: linux-mips <linux-mips@linux-mips.org>
Patchwork: http://patchwork.linux-mips.org/patch/1105/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
This commit is contained in:
Wu Zhangjin 2010-04-10 20:04:42 +08:00 committed by Ralf Baechle
parent c619366e36
commit 622844bf0b
1 changed files with 27 additions and 0 deletions
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27
arch/mips/Kconfig
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@ -1307,6 +1307,33 @@ config CPU_CAVIUM_OCTEON
endchoice
if CPU_LOONGSON2F
config CPU_NOP_WORKAROUNDS
bool
config CPU_JUMP_WORKAROUNDS
bool
config CPU_LOONGSON2F_WORKAROUNDS
bool "Loongson 2F Workarounds"
default y
select CPU_NOP_WORKAROUNDS
select CPU_JUMP_WORKAROUNDS
help
Loongson 2F01 / 2F02 processors have the NOP & JUMP issues which
require workarounds. Without workarounds the system may hang
unexpectedly. For more information please refer to the gas
-mfix-loongson2f-nop and -mfix-loongson2f-jump options.
Loongson 2F03 and later have fixed these issues and no workarounds
are needed. The workarounds have no significant side effect on them
but may decrease the performance of the system so this option should
be disabled unless the kernel is intended to be run on 2F01 or 2F02
systems.
If unsure, please say Y.
endif # CPU_LOONGSON2F
config SYS_SUPPORTS_ZBOOT
bool
select HAVE_KERNEL_GZIP