On 2018/11/30 下午8:45, Paul Hua wrote:
In some older Loongson3 processors there is a LL/SC errata that can
cause the CPU to deadlock occasionally. The details are very
complicated. We find a way to work around this errata by a) adding a
sync before ll/lld instruction, b) adding a sync
before branch target that between ll and sc. The assembler do the jobs
'a', gcc do the jobs 'b'.
Hi all,
Any update about this patch?
As this workaround is the last barrier for generic MIPS distros to run
on Loongson systems.
Btw, I heard from Loongson guys that type A (adding a sync before ll/lld
instruction) of this errata only exist on pre-3A2000 (GS464) processors
while type B exist on all processors. Is that true?
If so, then they should have different naming in flags to prevent
confusing. I saw that you are using "LLTGT" and "LLSYNC" in cpucfg bit
domin of 3A4000, should we also use that naming in toolchain?
Thanks.
--
Jiaxun Yang
This patch also add a configure options
--with-mips-fix-loongson3-llsc=[yes|no] to enable fix-loongson3-llsc
by config.
>From 16f0fd9e32d2098637dc0eb3e576444c48c43f22 Mon Sep 17 00:00:00 2001
From: Chenghua Xu <paul.hua...@gmail.com>
Date: Fri, 30 Nov 2018 19:57:38 +0800
Subject: [PATCH] [MIPS][GCC] Fix Loongson3 LLSC Errata.
gcc/
* config.gcc (supported_defaults): Add fix-loongson3-llsc
(with_fix_loongson3_llsc): Add validation.
(all_defaults): Add fix-loongson3-llsc.
* config/mips/mips.c (mips_process_sync_loop): Add sync before
branch target that between ll and sc.
* config/mips/mips.h (OPTION_DEFAULT_SPECS): Add a default for
fix-loongson3-llsc.
gcc/config/mips/mips.opt: New option.
* doc/install.texi (--with-fix-loongson3-llsc):Document the new
option.
* doc/invoke.texi (-mfix-loongson3-llsc):Document the new option.
gcc/testsuite/
* gcc.target/mips/fix-loongson3-llsc.c: New test.
* gcc.target/mips/mips.exp (option): Add fix-loongson3-llsc.
---
gcc/config.gcc | 19 +++++++++++++++++--
gcc/config/mips/mips.c | 13 +++++++++++--
gcc/config/mips/mips.h | 4 +++-
gcc/config/mips/mips.opt | 4 ++++
gcc/doc/install.texi | 4 ++++
gcc/doc/invoke.texi | 8 ++++++++
.../gcc.target/mips/fix-loongson3-llsc.c | 10 ++++++++++
gcc/testsuite/gcc.target/mips/mips.exp | 1 +
8 files changed, 58 insertions(+), 5 deletions(-)
create mode 100644 gcc/testsuite/gcc.target/mips/fix-loongson3-llsc.c
